diff --git a/apps/rowboat/app/actions/actions.ts b/apps/rowboat/app/actions/actions.ts
index 6ebd5fd4..eb694019 100644
--- a/apps/rowboat/app/actions/actions.ts
+++ b/apps/rowboat/app/actions/actions.ts
@@ -99,13 +99,13 @@ export async function getAssistantResponse(
     };
 }
 
-export async function suggestToolResponse(toolId: string, projectId: string, messages: z.infer<typeof apiV1.ChatMessage>[], testProfile: z.infer<typeof TestProfile>): Promise<string> {
+export async function suggestToolResponse(toolId: string, projectId: string, messages: z.infer<typeof apiV1.ChatMessage>[], mockInstructions: string): Promise<string> {
     await projectAuthCheck(projectId);
     if (!await check_query_limit(projectId)) {
         throw new QueryLimitError();
     }
 
-    return await mockToolResponse(toolId, messages, testProfile);
+    return await mockToolResponse(toolId, messages, mockInstructions);
 }
 
 export async function getInformationTool(
diff --git a/apps/rowboat/app/actions/project_actions.ts b/apps/rowboat/app/actions/project_actions.ts
index c5016b70..286d79c2 100644
--- a/apps/rowboat/app/actions/project_actions.ts
+++ b/apps/rowboat/app/actions/project_actions.ts
@@ -41,7 +41,6 @@ export async function createProject(formData: FormData) {
     const projectId = crypto.randomUUID();
     const chatClientId = crypto.randomBytes(16).toString('base64url');
     const secret = crypto.randomBytes(32).toString('hex');
-    const defaultTestProfileId = new ObjectId();
 
     // create project
     await projectsCollection.insertOne({
@@ -54,7 +53,6 @@ export async function createProject(formData: FormData) {
         secret,
         nextWorkflowNumber: 1,
         testRunCounter: 0,
-        defaultTestProfileId: defaultTestProfileId.toString(),
     });
 
     // add first workflow version
@@ -70,17 +68,6 @@ export async function createProject(formData: FormData) {
         name: `Version 1`,
     });
 
-    // add default test profile
-    await testProfilesCollection.insertOne({
-        _id: defaultTestProfileId,
-        projectId,
-        name: "Default",
-        context: "",
-        mockTools: false,
-        createdAt: (new Date()).toISOString(),
-        lastUpdatedAt: (new Date()).toISOString(),
-    });
-
     // add user to project
     await projectMembersCollection.insertOne({
         userId: user.sub,
diff --git a/apps/rowboat/app/actions/testing_actions.ts b/apps/rowboat/app/actions/testing_actions.ts
index 88f01142..c697b483 100644
--- a/apps/rowboat/app/actions/testing_actions.ts
+++ b/apps/rowboat/app/actions/testing_actions.ts
@@ -171,13 +171,13 @@ export async function createSimulation(
     data: {
         name: string;
         scenarioId: string;
-        profileId: string;
+        profileId: string | null;
         passCriteria: string;
     }
 ): Promise<WithStringId<z.infer<typeof TestSimulation>>> {
     await projectAuthCheck(projectId);
 
-    const doc = {
+    const doc: z.infer<typeof TestSimulation> = {
         ...data,
         projectId,
         createdAt: new Date().toISOString(),
@@ -196,7 +196,7 @@ export async function updateSimulation(
     updates: {
         name?: string;
         scenarioId?: string;
-        profileId?: string;
+        profileId?: string | null;
         passCriteria?: string;
     }
 ): Promise<void> {
@@ -245,34 +245,6 @@ export async function listProfiles(
     };
 }
 
-export async function getDefaultProfile(projectId: string): Promise<WithStringId<z.infer<typeof TestProfile>> | null> {
-    await projectAuthCheck(projectId);
-    const project = await projectsCollection.findOne({ _id: projectId });
-    if (!project) {
-        return null;
-    }
-    if (!project.defaultTestProfileId) {
-        // create a default profile
-        const profile = await createProfile(projectId, {
-            name: 'Default',
-            context: '',
-            mockTools: false,
-            mockPrompt: '',
-        });
-        await setDefaultProfile(projectId, profile._id);
-        return profile;
-    }
-    return getProfile(projectId, project.defaultTestProfileId);
-}
-
-export async function setDefaultProfile(projectId: string, profileId: string): Promise<void> {
-    await projectAuthCheck(projectId);
-    await projectsCollection.updateOne(
-        { _id: projectId },
-        { $set: { defaultTestProfileId: profileId } }
-    );
-}
-
 export async function getProfile(projectId: string, profileId: string): Promise<WithStringId<z.infer<typeof TestProfile>> | null> {
     await projectAuthCheck(projectId);
     
diff --git a/apps/rowboat/app/api/v1/[projectId]/chat/route.ts b/apps/rowboat/app/api/v1/[projectId]/chat/route.ts
index 1d7e8257..8047f40d 100644
--- a/apps/rowboat/app/api/v1/[projectId]/chat/route.ts
+++ b/apps/rowboat/app/api/v1/[projectId]/chat/route.ts
@@ -72,9 +72,9 @@ export async function POST(
         }
         
         // if test profile is provided in the request, use it
-        let profile: z.infer<typeof TestProfile> | null = null;
+        let testProfile: z.infer<typeof TestProfile> | null = null;
         if (result.data.testProfileId) {
-            const testProfile = await testProfilesCollection.findOne({
+            testProfile = await testProfilesCollection.findOne({
                 projectId: projectId,
                 _id: new ObjectId(result.data.testProfileId),
             });
@@ -82,34 +82,18 @@ export async function POST(
                 logger.log(`Test profile ${result.data.testProfileId} not found for project ${projectId}`);
                 return Response.json({ error: "Test profile not found" }, { status: 404 });
             }
-            profile = testProfile;
-        } else {
-            // if no test profile is provided, use the default profile
-            const defaultProfile = await testProfilesCollection.findOne({
-                projectId: projectId,
-                _id: new ObjectId(project.defaultTestProfileId),
-            });
-            if (!defaultProfile) {
-                logger.log(`Default test profile not found for project ${projectId}`);
-                return Response.json({ error: "Default test profile not found" }, { status: 404 });
-            }
-            profile = defaultProfile;
-        }
-        if (!profile) {
-            logger.log(`No test profile found for project ${projectId}`);
-            return Response.json({ error: "No test profile found" }, { status: 404 });
         }
 
         // if profile has a context available, overwrite the system message in the request (if there is one)
         let currentMessages = reqMessages;
-        if (profile.context) {
+        if (testProfile?.context) {
             // if there is a system message, overwrite it
             const systemMessageIndex = reqMessages.findIndex(m => m.role === "system");
             if (systemMessageIndex !== -1) {
-                currentMessages[systemMessageIndex].content = profile.context;
+                currentMessages[systemMessageIndex].content = testProfile.context;
             } else {
                 // if there is no system message, add one
-                currentMessages.unshift({ role: "system", content: profile.context });
+                currentMessages.unshift({ role: "system", content: testProfile.context });
             }
         }
 
@@ -183,9 +167,9 @@ export async function POST(
                         try {
                             // if tool is supposed to be mocked, mock it
                             const workflowTool = workflow.tools.find(t => t.name === toolCall.function.name);
-                            if (profile.mockTools) {
+                            if (testProfile?.mockTools || workflowTool?.mockTool) {
                                 logger.log(`Mocking tool call ${toolCall.function.name}`);
-                                result = await mockToolResponse(toolCall.id, currentMessages, profile);
+                                result = await mockToolResponse(toolCall.id, currentMessages, testProfile?.mockPrompt || workflowTool?.mockInstructions || '');
                             } else {
                                 // else run the tool call by calling the client tool webhook
                                 logger.log(`Running client tool webhook for tool ${toolCall.function.name}`);
diff --git a/apps/rowboat/app/lib/project_templates.ts b/apps/rowboat/app/lib/project_templates.ts
index 505bffab..1a9427b1 100644
--- a/apps/rowboat/app/lib/project_templates.ts
+++ b/apps/rowboat/app/lib/project_templates.ts
@@ -147,7 +147,7 @@ You are an helpful customer support assistant
                         "user_id"
                     ]
             },
-            "mockInPlayground": true,
+            "mockTool": true,
             "autoSubmitMockedResponse": true
             },
             {
@@ -165,7 +165,7 @@ You are an helpful customer support assistant
                         "param1"
                     ]
                 },
-            "mockInPlayground": true,
+            "mockTool": true,
             "autoSubmitMockedResponse": true
             }
         ],
@@ -289,13 +289,13 @@ You are an helpful customer support assistant
                     "orderId"
                     ]
                 },
-                "mockInPlayground": true,
+                "mockTool": true,
                 "autoSubmitMockedResponse": true
             },
             {
                 "name": "retrieve_snippet",
                 "description": "This is a mock RAG service. Always return 2 paragraphs about a fictional scooter rental product, based on the query. Be verbose.",
-                "mockInPlayground": true,
+                "mockTool": true,
                 "autoSubmitMockedResponse": true,
                 "parameters": {
                     "type": "object",
@@ -325,7 +325,7 @@ You are an helpful customer support assistant
                         "orderId"
                     ]
                 },
-                "mockInPlayground": true,
+                "mockTool": true,
                 "autoSubmitMockedResponse": true
             }
         ],
diff --git a/apps/rowboat/app/lib/types/agents_api_types.ts b/apps/rowboat/app/lib/types/agents_api_types.ts
index 42e9e950..5fd45758 100644
--- a/apps/rowboat/app/lib/types/agents_api_types.ts
+++ b/apps/rowboat/app/lib/types/agents_api_types.ts
@@ -44,7 +44,7 @@ export const AgenticAPIAgent = WorkflowAgent
 export const AgenticAPIPrompt = WorkflowPrompt;
 
 export const AgenticAPITool = WorkflowTool.omit({
-    mockInPlayground: true,
+    mockTool: true,
     autoSubmitMockedResponse: true,
 });
 
@@ -91,7 +91,7 @@ export function convertWorkflowToAgenticAPI(workflow: z.infer<typeof Workflow>):
                 return agenticAgent;
             }),
         tools: workflow.tools.map(tool => {
-            const { mockInPlayground, autoSubmitMockedResponse, ...rest } = tool;
+            const { mockTool, autoSubmitMockedResponse, ...rest } = tool;
             return {
                 ...rest,
             };
diff --git a/apps/rowboat/app/lib/types/project_types.ts b/apps/rowboat/app/lib/types/project_types.ts
index b426ed6c..50df41b4 100644
--- a/apps/rowboat/app/lib/types/project_types.ts
+++ b/apps/rowboat/app/lib/types/project_types.ts
@@ -11,7 +11,6 @@ export const Project = z.object({
     publishedWorkflowId: z.string().optional(),
     nextWorkflowNumber: z.number().optional(),
     testRunCounter: z.number().default(0),
-    defaultTestProfileId: z.string().optional(),
 });export const ProjectMember = z.object({
     userId: z.string(),
     projectId: z.string(),
diff --git a/apps/rowboat/app/lib/types/testing_types.ts b/apps/rowboat/app/lib/types/testing_types.ts
index 4a1440bb..ff544517 100644
--- a/apps/rowboat/app/lib/types/testing_types.ts
+++ b/apps/rowboat/app/lib/types/testing_types.ts
@@ -22,7 +22,7 @@ export const TestSimulation = z.object({
     projectId: z.string(),
     name: z.string().min(1, "Name cannot be empty"),
     scenarioId: z.string(),
-    profileId: z.string(),
+    profileId: z.string().nullable(),
     passCriteria: z.string(),
     createdAt: z.string().datetime(),
     lastUpdatedAt: z.string().datetime(),
diff --git a/apps/rowboat/app/lib/types/workflow_types.ts b/apps/rowboat/app/lib/types/workflow_types.ts
index 46554c36..160fc645 100644
--- a/apps/rowboat/app/lib/types/workflow_types.ts
+++ b/apps/rowboat/app/lib/types/workflow_types.ts
@@ -33,8 +33,9 @@ export const WorkflowPrompt = z.object({
 export const WorkflowTool = z.object({
     name: z.string(),
     description: z.string(),
-    mockInPlayground: z.boolean().default(false).optional(),
+    mockTool: z.boolean().default(false).optional(),
     autoSubmitMockedResponse: z.boolean().default(false).optional(),
+    mockInstructions: z.string().optional(),
     parameters: z.object({
         type: z.literal('object'),
         properties: z.record(z.object({
diff --git a/apps/rowboat/app/lib/utils.ts b/apps/rowboat/app/lib/utils.ts
index f371eb74..d72088c2 100644
--- a/apps/rowboat/app/lib/utils.ts
+++ b/apps/rowboat/app/lib/utils.ts
@@ -221,7 +221,7 @@ export class PrefixLogger {
     }
 }
 
-export async function mockToolResponse(toolId: string, messages: z.infer<typeof ApiMessage>[], testProfile: z.infer<typeof TestProfile>): Promise<string> {
+export async function mockToolResponse(toolId: string, messages: z.infer<typeof ApiMessage>[], mockInstructions: string): Promise<string> {
     const prompt = `Given below is a chat between a user and a customer support assistant.
 The assistant has requested a tool call with ID {{toolID}}.
 
@@ -234,10 +234,6 @@ and also some instructions on how to mock the tool call.
 {{messages}}
 <<<END_OF_CHAT_HISTORY
 
->>>CONTEXT
-{{context}}
-<<<END_OF_CONTEXT
-
 >>>MOCK_INSTRUCTIONS
 {{mockInstructions}}
 <<<END_OF_MOCK_INSTRUCTIONS
@@ -246,8 +242,7 @@ The current date is {{date}}.
 `
         .replace('{{toolID}}', toolId)
         .replace(`{{date}}`, new Date().toISOString())
-        .replace('{{context}}', testProfile.context)
-        .replace('{{mockInstructions}}', testProfile.mockPrompt || '')
+        .replace('{{mockInstructions}}', mockInstructions)
         .replace('{{messages}}', JSON.stringify(messages.map((m) => {
             let tool_calls;
             if ('tool_calls' in m && m.role == 'assistant') {
diff --git a/apps/rowboat/app/projects/[projectId]/playground/app.tsx b/apps/rowboat/app/projects/[projectId]/playground/app.tsx
index 0c27bd39..e46bf6d6 100644
--- a/apps/rowboat/app/projects/[projectId]/playground/app.tsx
+++ b/apps/rowboat/app/projects/[projectId]/playground/app.tsx
@@ -24,16 +24,14 @@ export function App({
     projectId,
     workflow,
     messageSubscriber,
-    initialTestProfile,
 }: {
     hidden?: boolean;
     projectId: string;
     workflow: z.infer<typeof Workflow>;
     messageSubscriber?: (messages: z.infer<typeof apiV1.ChatMessage>[]) => void;
-    initialTestProfile: z.infer<typeof TestProfile>;
 }) {
     const [counter, setCounter] = useState<number>(0);
-    const [testProfile, setTestProfile] = useState<z.infer<typeof TestProfile>>(initialTestProfile);
+    const [testProfile, setTestProfile] = useState<z.infer<typeof TestProfile> | null>(null);
     const [chat, setChat] = useState<z.infer<typeof PlaygroundChat>>({
         projectId,
         createdAt: new Date().toISOString(),
@@ -42,7 +40,7 @@ export function App({
         systemMessage: defaultSystemMessage,
     });
 
-    function handleTestProfileChange(profile: WithStringId<z.infer<typeof TestProfile>>) {
+    function handleTestProfileChange(profile: WithStringId<z.infer<typeof TestProfile>> | null) {
         setTestProfile(profile);
         setCounter(counter + 1);
     }
diff --git a/apps/rowboat/app/projects/[projectId]/playground/chat.tsx b/apps/rowboat/app/projects/[projectId]/playground/chat.tsx
index ea9bf9fa..3e348668 100644
--- a/apps/rowboat/app/projects/[projectId]/playground/chat.tsx
+++ b/apps/rowboat/app/projects/[projectId]/playground/chat.tsx
@@ -15,21 +15,22 @@ import { CopyAsJsonButton } from "./copy-as-json-button";
 import { TestProfile } from "@/app/lib/types/testing_types";
 import { ProfileSelector } from "@/app/lib/components/selectors/profile-selector";
 import { WithStringId } from "@/app/lib/types/types";
+import { XCircleIcon, XIcon } from "lucide-react";
 
 export function Chat({
     chat,
     projectId,
     workflow,
     messageSubscriber,
-    testProfile,
+    testProfile=null,
     onTestProfileChange,
 }: {
     chat: z.infer<typeof PlaygroundChat>;
     projectId: string;
     workflow: z.infer<typeof Workflow>;
     messageSubscriber?: (messages: z.infer<typeof apiV1.ChatMessage>[]) => void;
-    testProfile: z.infer<typeof TestProfile>;
-    onTestProfileChange: (profile: WithStringId<z.infer<typeof TestProfile>>) => void;
+    testProfile?: z.infer<typeof TestProfile> | null;
+    onTestProfileChange: (profile: WithStringId<z.infer<typeof TestProfile>> | null) => void;
 }) {
     const [messages, setMessages] = useState<z.infer<typeof apiV1.ChatMessage>[]>(chat.messages);
     const [loadingAssistantResponse, setLoadingAssistantResponse] = useState<boolean>(false);
@@ -41,7 +42,7 @@ export function Chat({
     const [fetchResponseError, setFetchResponseError] = useState<string | null>(null);
     const [lastAgenticRequest, setLastAgenticRequest] = useState<unknown | null>(null);
     const [lastAgenticResponse, setLastAgenticResponse] = useState<unknown | null>(null);
-    const [systemMessage, setSystemMessage] = useState<string | undefined>(testProfile.context);
+    const [systemMessage, setSystemMessage] = useState<string | undefined>(testProfile?.context);
     const [isProfileSelectorOpen, setIsProfileSelectorOpen] = useState(false);
 
     // collect published tool call results
@@ -279,15 +280,20 @@ export function Chat({
 
     return <div className="relative h-full flex flex-col gap-8 pt-8 overflow-auto">
         <CopyAsJsonButton onCopy={handleCopyChat} />
-        <div className="absolute top-0 left-0">
+        <div className="absolute top-0 left-0 flex items-center gap-1">
             <Tooltip content={"Change profile"} placement="right">
                 <button
                     className="border border-gray-200 dark:border-gray-800 p-2 rounded-lg text-xs hover:bg-gray-100 dark:hover:bg-gray-800"
                     onClick={() => setIsProfileSelectorOpen(true)}
                 >
-                    {`Test profile: ${testProfile.name}`}
+                    {`${testProfile?.name || 'Select test profile'}`}
                 </button>
             </Tooltip>
+            {testProfile && <Tooltip content={"Remove profile"} placement="right">
+                <button className="text-gray-500 dark:text-gray-400 hover:text-gray-700 dark:hover:text-gray-300" onClick={() => onTestProfileChange(null)}>
+                    <XIcon className="w-4 h-4" />
+                </button>
+            </Tooltip>}
         </div>
         <ProfileSelector
             projectId={projectId}
diff --git a/apps/rowboat/app/projects/[projectId]/playground/messages.tsx b/apps/rowboat/app/projects/[projectId]/playground/messages.tsx
index 0f6166a2..fc3fea1a 100644
--- a/apps/rowboat/app/projects/[projectId]/playground/messages.tsx
+++ b/apps/rowboat/app/projects/[projectId]/playground/messages.tsx
@@ -94,7 +94,8 @@ function ToolCalls({
     messages,
     sender,
     workflow,
-    testProfile,
+    testProfile=null,
+    systemMessage,
 }: {
     toolCalls: z.infer<typeof apiV1.AssistantMessageWithToolCalls>['tool_calls'];
     results: Record<string, z.infer<typeof apiV1.ToolMessage>>;
@@ -103,7 +104,8 @@ function ToolCalls({
     messages: z.infer<typeof apiV1.ChatMessage>[];
     sender: string | null | undefined;
     workflow: z.infer<typeof Workflow>;
-    testProfile: z.infer<typeof TestProfile>;
+    testProfile: z.infer<typeof TestProfile> | null;
+    systemMessage: string | undefined;
 }) {
     const resultsMap: Record<string, z.infer<typeof apiV1.ToolMessage>> = {};
 
@@ -127,6 +129,7 @@ function ToolCalls({
                 sender={sender}
                 workflow={workflow}
                 testProfile={testProfile}
+                systemMessage={systemMessage}
             />
         })}
     </div>;
@@ -140,7 +143,8 @@ function ToolCall({
     messages,
     sender,
     workflow,
-    testProfile,
+    testProfile=null,
+    systemMessage,
 }: {
     toolCall: z.infer<typeof apiV1.AssistantMessageWithToolCalls>['tool_calls'][number];
     result: z.infer<typeof apiV1.ToolMessage> | undefined;
@@ -149,7 +153,8 @@ function ToolCall({
     messages: z.infer<typeof apiV1.ChatMessage>[];
     sender: string | null | undefined;
     workflow: z.infer<typeof Workflow>;
-    testProfile: z.infer<typeof TestProfile>;
+    testProfile: z.infer<typeof TestProfile> | null;
+    systemMessage: string | undefined;
 }) {
     let matchingWorkflowTool: z.infer<typeof WorkflowTool> | undefined;
     for (const tool of workflow.tools) {
@@ -181,7 +186,7 @@ function ToolCall({
                     sender={sender}
                 />;
             }
-            if (matchingWorkflowTool && !testProfile.mockTools) {
+            if (matchingWorkflowTool && testProfile && !testProfile.mockTools) {
                 return <ClientToolCall
                     toolCall={toolCall}
                     result={result}
@@ -198,8 +203,9 @@ function ToolCall({
                 projectId={projectId}
                 messages={messages}
                 sender={sender}
-                autoSubmit={matchingWorkflowTool?.autoSubmitMockedResponse}
                 testProfile={testProfile}
+                workflowTool={matchingWorkflowTool}
+                systemMessage={systemMessage}
             />;
     }
 }
@@ -413,8 +419,9 @@ function MockToolCall({
     projectId,
     messages,
     sender,
-    autoSubmit = false,
-    testProfile,
+    testProfile=null,
+    workflowTool,
+    systemMessage,
 }: {
     toolCall: z.infer<typeof apiV1.AssistantMessageWithToolCalls>['tool_calls'][number];
     result: z.infer<typeof apiV1.ToolMessage> | undefined;
@@ -422,8 +429,9 @@ function MockToolCall({
     projectId: string;
     messages: z.infer<typeof apiV1.ChatMessage>[];
     sender: string | null | undefined;
-    autoSubmit?: boolean;
-    testProfile: z.infer<typeof TestProfile>;
+    testProfile: z.infer<typeof TestProfile> | null;
+    workflowTool: z.infer<typeof WorkflowTool> | undefined;
+    systemMessage: string | undefined;
 }) {
     const [result, setResult] = useState<z.infer<typeof apiV1.ToolMessage> | undefined>(availableResult);
     const [response, setResponse] = useState('');
@@ -459,7 +467,18 @@ function MockToolCall({
         async function process() {
             setGeneratingResponse(true);
 
-            const response = await suggestToolResponse(toolCall.id, projectId, messages, testProfile);
+            const response = await suggestToolResponse(
+                toolCall.id,
+                projectId,
+                [{
+                    role: 'system',
+                    content: systemMessage || '',
+                    createdAt: new Date().toISOString(),
+                    version: 'v1',
+                    chatId: '',
+                }, ...messages],
+                testProfile?.mockPrompt || workflowTool?.mockInstructions || '',
+            );
             if (ignore) {
                 return;
             }
@@ -471,11 +490,11 @@ function MockToolCall({
         return () => {
             ignore = true;
         };
-    }, [result, response, toolCall.id, projectId, messages, testProfile]);
+    }, [result, response, toolCall.id, projectId, messages, testProfile, systemMessage, workflowTool?.mockInstructions]);
 
     // auto submit if autoSubmitMockedResponse is true
     useEffect(() => {
-        if (!autoSubmit) {
+        if (!workflowTool?.autoSubmitMockedResponse) {
             return;
         }
         if (result) {
@@ -484,13 +503,14 @@ function MockToolCall({
         if (response) {
             handleSubmit();
         }
-    }, [autoSubmit, response, handleSubmit, result]);
+    }, [workflowTool?.autoSubmitMockedResponse, response, handleSubmit, result]);
 
     return <div className="flex flex-col gap-1">
         {sender && <div className='text-gray-500 dark:text-gray-400 text-xs ml-3'>{sender}</div>}
         <div className='border border-gray-300 dark:border-gray-700 p-2 pt-2 rounded-lg rounded-bl-none flex flex-col gap-2 mr-[30%] bg-white dark:bg-gray-900'>
             <div className="flex items-center gap-2">
-                <CircleCheckIcon size={16} className="text-gray-500 dark:text-gray-400" />
+                {!result && <Spinner size="sm" />}
+                {result && <CircleCheckIcon size={16} className="text-gray-500 dark:text-gray-400" />}
                 <span className="text-sm text-gray-700 dark:text-gray-300">
                     Function Call: <code className='bg-gray-100 dark:bg-neutral-800 px-2 py-0.5 rounded font-mono'>{toolCall.function.name}</code>
                 </span>
@@ -501,7 +521,7 @@ function MockToolCall({
                 {result && <ExpandableContent label='Result' content={result.content} expanded={false} />}
             </div>
 
-            {!result && !autoSubmit && <div className='flex flex-col gap-2 mt-2'>
+            {!result && !workflowTool?.autoSubmitMockedResponse && <div className='flex flex-col gap-2 mt-2'>
                 <div>Response:</div>
                 <Textarea
                     maxRows={10}
@@ -603,7 +623,7 @@ export function Messages({
     loadingAssistantResponse,
     loadingUserResponse,
     workflow,
-    testProfile,
+    testProfile=null,
     onSystemMessageChange,
 }: {
     projectId: string;
@@ -614,7 +634,7 @@ export function Messages({
     loadingAssistantResponse: boolean;
     loadingUserResponse: boolean;
     workflow: z.infer<typeof Workflow>;
-    testProfile: z.infer<typeof TestProfile>;
+    testProfile: z.infer<typeof TestProfile> | null;
     onSystemMessageChange: (message: string) => void;
 }) {
     const messagesEndRef = useRef<HTMLDivElement>(null);
@@ -628,9 +648,9 @@ export function Messages({
     return <div className="grow pt-4 overflow-auto">
         <div className="max-w-[768px] mx-auto flex flex-col gap-8">
             <SystemMessage
-                content={testProfile.context}
+                content={testProfile?.context || systemMessage || ''}
                 onChange={onSystemMessageChange}
-                locked={true}
+                locked={testProfile !== null || messages.length > 0}
             />
             {messages.map((message, index) => {
                 if (message.role === 'assistant') {
@@ -645,6 +665,7 @@ export function Messages({
                             sender={message.agenticSender}
                             workflow={workflow}
                             testProfile={testProfile}
+                            systemMessage={systemMessage}
                         />;
                     } else {
                         // the assistant message createdAt is an ISO string timestamp
diff --git a/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/profiles_app.tsx b/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/profiles_app.tsx
index e8dbbd61..a630e13d 100644
--- a/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/profiles_app.tsx
+++ b/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/profiles_app.tsx
@@ -2,7 +2,7 @@ import Link from "next/link";
 import { WithStringId } from "@/app/lib/types/types";
 import { TestProfile } from "@/app/lib/types/testing_types";
 import { useEffect, useState, useRef } from "react";
-import { createProfile, getProfile, listProfiles, updateProfile, deleteProfile, setDefaultProfile } from "@/app/actions/testing_actions";
+import { createProfile, getProfile, listProfiles, updateProfile, deleteProfile } from "@/app/actions/testing_actions";
 import { Button, Input, Pagination, Spinner, Switch, Textarea, Modal, ModalContent, ModalHeader, ModalBody, ModalFooter, Tooltip } from "@heroui/react";
 import { useRouter, useSearchParams } from "next/navigation";
 import { z } from "zod";
@@ -134,7 +134,6 @@ function ViewProfile({
 }) {
     const router = useRouter();
     const [profile, setProfile] = useState<WithStringId<z.infer<typeof TestProfile>> | null>(null);
-    const [defaultProfileId, setDefaultProfileId] = useState<string | null>(null);
     const [loading, setLoading] = useState(true);
     const [isDeleteModalOpen, setIsDeleteModalOpen] = useState(false);
     const [deleteError, setDeleteError] = useState<string | null>(null);
@@ -142,9 +141,7 @@ function ViewProfile({
     useEffect(() => {
         async function fetchProfile() {
             const profile = await getProfile(projectId, profileId);
-            const projectConfig = await getProjectConfig(projectId);
             setProfile(profile);
-            setDefaultProfileId(projectConfig.defaultTestProfileId || null);
             setLoading(false);
         }
         fetchProfile();
@@ -159,11 +156,6 @@ function ViewProfile({
         }
     }
 
-    async function handleSetDefault() {
-        await setDefaultProfile(projectId, profileId);
-        router.push(`/projects/${projectId}/test/profiles`);
-    }
-
     return <div className="h-full flex flex-col gap-2">
         <h1 className="text-medium font-bold text-gray-800 pb-2 border-b border-gray-200">View Profile</h1>
         <Button
@@ -186,13 +178,7 @@ function ViewProfile({
                     <div className="flex border-b py-2">
                         <div className="flex-[1] font-medium text-gray-600">Name</div>
                         <div className="flex-[2]">
-                            <div className="flex flex-col gap-2">
-                                <div>{profile.name}</div>
-                                {defaultProfileId === profile._id && <div className="flex items-center gap-2">
-                                    <StarIcon className="w-4 h-4" />
-                                    <div className="text-gray-600">This is the default profile</div>
-                                </div>}
-                            </div>
+                            <div className="flex-[2] whitespace-pre-wrap">{profile.name}</div>
                         </div>
                     </div>
                     <div className="flex border-b py-2">
@@ -224,21 +210,14 @@ function ViewProfile({
                     >
                         Edit
                     </Button>
-                    {defaultProfileId !== profile._id && <Button
+                    <Button
                         size="sm"
                         color="danger"
                         variant="flat"
                         onClick={() => setIsDeleteModalOpen(true)}
                     >
                         Delete
-                    </Button>}
-                    {defaultProfileId !== profile._id && <Button
-                        size="sm"
-                        onClick={() => handleSetDefault()}
-                        startContent={<StarIcon className="w-4 h-4" />}
-                    >
-                        Set as default profile
-                    </Button>}
+                    </Button>
                 </div>
 
                 <Modal
@@ -399,7 +378,6 @@ function ProfileList({
     const [loading, setLoading] = useState(true);
     const [error, setError] = useState<string | null>(null);
     const [profiles, setProfiles] = useState<WithStringId<z.infer<typeof TestProfile>>[]>([]);
-    const [defaultProfileId, setDefaultProfileId] = useState<string | null>(null);
     const [total, setTotal] = useState(0);
 
     useEffect(() => {
@@ -410,11 +388,9 @@ function ProfileList({
             setError(null);
             try {
                 const profiles = await listProfiles(projectId, page, pageSize);
-                const projectConfig = await getProjectConfig(projectId);
                 if (!ignore) {
                     setProfiles(profiles.profiles);
                     setTotal(Math.ceil(profiles.total / pageSize));
-                    setDefaultProfileId(projectConfig.defaultTestProfileId || null);
                 }
             } catch (error) {
                 if (!ignore) {
@@ -470,17 +446,12 @@ function ProfileList({
                 {profiles.map((profile) => (
                     <div key={profile._id} className="grid grid-cols-8 py-2 border-b hover:bg-gray-50 text-sm">
                         <div className="col-span-2 px-4 truncate">
-                            <div className="flex items-center gap-2">
-                                <Link
-                                    href={`/projects/${projectId}/test/profiles/${profile._id}`}
-                                    className="text-blue-600 hover:underline"
-                                >
-                                    {profile.name}
-                                </Link>
-                                {defaultProfileId === profile._id && <Tooltip content="Default Profile">
-                                    <StarIcon className="w-4 h-4" />
-                                </Tooltip>}
-                            </div>
+                            <Link
+                                href={`/projects/${projectId}/test/profiles/${profile._id}`}
+                                className="text-blue-600 hover:underline"
+                            >
+                                {profile.name}
+                            </Link>
                         </div>
                         <div className="col-span-3 px-4 truncate">{profile.context}</div>
                         <div className="col-span-1 px-4">{profile.mockTools ? "Yes" : "No"}</div>
diff --git a/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/simulations_app.tsx b/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/simulations_app.tsx
index fe0a562f..2fa1c47a 100644
--- a/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/simulations_app.tsx
+++ b/apps/rowboat/app/projects/[projectId]/test/[[...slug]]/simulations_app.tsx
@@ -38,7 +38,7 @@ function EditSimulation({
                 if (simulation) {
                     const [scenarioResult, profileResult] = await Promise.all([
                         getScenario(projectId, simulation.scenarioId),
-                        getProfile(projectId, simulation.profileId),
+                        simulation.profileId ? getProfile(projectId, simulation.profileId) : Promise.resolve(null),
                     ]);
                     setScenario(scenarioResult);
                     setProfile(profileResult);
@@ -62,14 +62,14 @@ function EditSimulation({
                 throw new Error("Name and Pass Criteria are required");
             }
 
-            if (!scenario || !profile) {
-                throw new Error("Please select all required fields");
+            if (!scenario) {
+                throw new Error("Please select a scenario");
             }
 
             await updateSimulation(projectId, simulationId, {
                 name,
                 scenarioId: scenario._id,
-                profileId: profile._id,
+                profileId: profile?._id || null,
                 passCriteria
             });
             router.push(`/projects/${projectId}/test/simulations/${simulationId}`);
@@ -124,13 +124,14 @@ function EditSimulation({
                     </div>
                 </div>
                 <div className="flex flex-col gap-2">
-                    <label className="text-sm font-medium">Profile</label>
+                    <label className="text-sm font-medium">Profile (optional)</label>
                     <div className="flex items-center gap-2">
                         {profile ? (
                             <div className="text-sm text-blue-600">{profile.name}</div>
                         ) : (
                             <div className="text-sm text-gray-500">No profile selected</div>
                         )}
+                        {profile && <Button size="sm" variant="bordered" onClick={() => setProfile(null)}>Remove</Button>}
                         <Button
                             size="sm"
                             onClick={() => setIsProfileModalOpen(true)}
@@ -147,7 +148,7 @@ function EditSimulation({
                             children: "Update",
                             size: "sm",
                             type: "submit",
-                            isDisabled: !scenario || !profile,
+                            isDisabled: !scenario,
                         }}
                     />
                     <Button
@@ -199,7 +200,7 @@ function ViewSimulation({
             if (simulation) {
                 const [scenarioResult, profileResult] = await Promise.all([
                     getScenario(projectId, simulation.scenarioId),
-                    getProfile(projectId, simulation.profileId),
+                    simulation.profileId ? getProfile(projectId, simulation.profileId) : Promise.resolve(null),
                 ]);
                 setScenario(scenarioResult);
                 setProfile(profileResult);
@@ -384,14 +385,11 @@ function NewSimulation({
             if (!scenario) {
                 throw new Error("Please select a scenario");
             }
-            if (!profile) {
-                throw new Error("Please select a profile");
-            }
 
             const result = await createSimulation(projectId, {
                 name,
                 scenarioId: scenario._id,
-                profileId: profile._id,
+                profileId: profile?._id || null,
                 passCriteria,
             });
             router.push(`/projects/${projectId}/test/simulations/${result._id}`);
@@ -448,13 +446,14 @@ function NewSimulation({
                 </div>
             </div>
             <div className="flex flex-col gap-2">
-                <label className="text-sm font-medium">Profile</label>
+                <label className="text-sm font-medium">Profile (optional)</label>
                 <div className="flex items-center gap-2">
                     {profile ? (
                         <div className="text-sm text-blue-600">{profile.name}</div>
                     ) : (
                         <div className="text-sm text-gray-500">No profile selected</div>
                     )}
+                    {profile && <Button size="sm" variant="bordered" onClick={() => setProfile(null)}>Remove</Button>}
                     <Button
                         size="sm"
                         onClick={() => setIsProfileModalOpen(true)}
@@ -470,7 +469,7 @@ function NewSimulation({
                     children: "Create",
                     size: "sm",
                     type: "submit",
-                    isDisabled: !scenario || !profile,
+                    isDisabled: !scenario,
                 }}
             />
         </form>
@@ -559,7 +558,7 @@ function SimulationList({
         }
         async function resolveProfiles() {
             const profileIds = simulationList.reduce((acc, simulation) => {
-                if (!acc.includes(simulation.profileId)) {
+                if (simulation.profileId && !acc.includes(simulation.profileId)) {
                     acc.push(simulation.profileId);
                 }
                 return acc;
@@ -632,8 +631,12 @@ function SimulationList({
                             )}
                         </div>
                         <div className="col-span-1 px-4 truncate">
-                            {profileMap[simulation.profileId]?.name || (
-                                <span className="text-gray-500 font-mono text-xs">{simulation.profileId}</span>
+                            {simulation.profileId ? (
+                                profileMap[simulation.profileId]?.name || (
+                                    <span className="text-gray-500 font-mono text-xs">{simulation.profileId}</span>
+                                )
+                            ) : (
+                                <span className="text-gray-500 font-mono text-xs">None</span>
                             )}
                         </div>
                         <div className="col-span-1 px-4 truncate">
diff --git a/apps/rowboat/app/projects/[projectId]/workflow/app.tsx b/apps/rowboat/app/projects/[projectId]/workflow/app.tsx
index f9b7e57e..df8a18cb 100644
--- a/apps/rowboat/app/projects/[projectId]/workflow/app.tsx
+++ b/apps/rowboat/app/projects/[projectId]/workflow/app.tsx
@@ -10,7 +10,6 @@ import { Spinner } from "@heroui/react";
 import { cloneWorkflow, createWorkflow, fetchPublishedWorkflowId, fetchWorkflow } from "../../../actions/workflow_actions";
 import { listDataSources } from "../../../actions/datasource_actions";
 import { TestProfile } from "@/app/lib/types/testing_types";
-import { getDefaultProfile } from "../../../actions/testing_actions";
 
 export function App({
     projectId,
@@ -21,7 +20,6 @@ export function App({
     const [workflow, setWorkflow] = useState<WithStringId<z.infer<typeof Workflow>> | null>(null);
     const [publishedWorkflowId, setPublishedWorkflowId] = useState<string | null>(null);
     const [dataSources, setDataSources] = useState<WithStringId<z.infer<typeof DataSource>>[] | null>(null);
-    const [defaultTestProfile, setDefaultTestProfile] = useState<z.infer<typeof TestProfile> | null>(null);
     const [loading, setLoading] = useState(false);
     const [autoSelectIfOnlyOneWorkflow, setAutoSelectIfOnlyOneWorkflow] = useState(true);
 
@@ -30,13 +28,11 @@ export function App({
         const workflow = await fetchWorkflow(projectId, workflowId);
         const publishedWorkflowId = await fetchPublishedWorkflowId(projectId);
         const dataSources = await listDataSources(projectId);
-        const defaultTestProfile = await getDefaultProfile(projectId);
         // Store the selected workflow ID in local storage
         localStorage.setItem(`lastWorkflowId_${projectId}`, workflowId);
         setWorkflow(workflow);
         setPublishedWorkflowId(publishedWorkflowId);
         setDataSources(dataSources);
-        setDefaultTestProfile(defaultTestProfile);
         setLoading(false);
     }, [projectId]);
 
@@ -52,13 +48,11 @@ export function App({
         const workflow = await createWorkflow(projectId);
         const publishedWorkflowId = await fetchPublishedWorkflowId(projectId);
         const dataSources = await listDataSources(projectId);
-        const testProfile = await getDefaultProfile(projectId);
         // Store the selected workflow ID in local storage
         localStorage.setItem(`lastWorkflowId_${projectId}`, workflow._id);
         setWorkflow(workflow);
         setPublishedWorkflowId(publishedWorkflowId);
         setDataSources(dataSources);
-        setDefaultTestProfile(testProfile);
         setLoading(false);
     }
 
@@ -67,13 +61,11 @@ export function App({
         const workflow = await cloneWorkflow(projectId, workflowId);
         const publishedWorkflowId = await fetchPublishedWorkflowId(projectId);
         const dataSources = await listDataSources(projectId);
-        const testProfile = await getDefaultProfile(projectId);
         // Store the selected workflow ID in local storage
         localStorage.setItem(`lastWorkflowId_${projectId}`, workflow._id);
         setWorkflow(workflow);
         setPublishedWorkflowId(publishedWorkflowId);
         setDataSources(dataSources);
-        setDefaultTestProfile(testProfile);
         setLoading(false);
     }
 
@@ -107,11 +99,10 @@ export function App({
             handleCreateNewVersion={handleCreateNewVersion}
             autoSelectIfOnlyOneWorkflow={autoSelectIfOnlyOneWorkflow}
         />}
-        {!loading && workflow && (dataSources !== null) && (defaultTestProfile !== null) && <WorkflowEditor
+        {!loading && workflow && (dataSources !== null) && <WorkflowEditor
             key={workflow._id}
             workflow={workflow}
             dataSources={dataSources}
-            initialTestProfile={defaultTestProfile}
             publishedWorkflowId={publishedWorkflowId}
             handleShowSelector={handleShowSelector}
             handleCloneVersion={handleCloneVersion}
diff --git a/apps/rowboat/app/projects/[projectId]/workflow/tool_config.tsx b/apps/rowboat/app/projects/[projectId]/workflow/tool_config.tsx
index 4427b41b..26296a14 100644
--- a/apps/rowboat/app/projects/[projectId]/workflow/tool_config.tsx
+++ b/apps/rowboat/app/projects/[projectId]/workflow/tool_config.tsx
@@ -230,10 +230,10 @@ export function ToolConfig({
                 <div className="ml-4 flex flex-col gap-2">
                     <RadioGroup
                         defaultValue="mock"
-                        value={tool.mockInPlayground ? "mock" : "api"}
+                        value={tool.mockTool ? "mock" : "api"}
                         onValueChange={(value) => handleUpdate({
                             ...tool,
-                            mockInPlayground: value === "mock",
+                            mockTool: value === "mock",
                             autoSubmitMockedResponse: value === "mock" ? true : undefined
                         })}
                         orientation="horizontal"
@@ -264,7 +264,7 @@ export function ToolConfig({
                         </Radio>
                     </RadioGroup>
 
-                    {tool.mockInPlayground && (
+                    {tool.mockTool && <>
                         <div className="ml-0">
                             <Checkbox
                                 key="autoSubmitMockedResponse"
@@ -281,9 +281,22 @@ export function ToolConfig({
                                 Auto-submit mocked response in playground
                             </Checkbox>
                         </div>
-                    )}
 
-                    {!tool.mockInPlayground && (
+                        <Divider />
+
+                        <EditableField
+                            label="Mock instructions"
+                            value={tool.mockInstructions || ''}
+                            onChange={(value) => handleUpdate({
+                                ...tool,
+                                mockInstructions: value
+                            })}
+                            placeholder="Enter mock instructions..."
+                            multiline
+                        />
+                    </>}
+
+                    {!tool.mockTool && (
                         <div className="ml-0 text-danger text-xs">
                             Please configure your webhook in the <strong>Integrate</strong> page if you haven&apos;t already.
                         </div>
diff --git a/apps/rowboat/app/projects/[projectId]/workflow/workflow_editor.tsx b/apps/rowboat/app/projects/[projectId]/workflow/workflow_editor.tsx
index bf37227c..d8f01970 100644
--- a/apps/rowboat/app/projects/[projectId]/workflow/workflow_editor.tsx
+++ b/apps/rowboat/app/projects/[projectId]/workflow/workflow_editor.tsx
@@ -285,7 +285,7 @@ function reducer(state: State, action: Action): State {
                                     type: "object",
                                     properties: {},
                                 },
-                                mockInPlayground: true,
+                                mockTool: true,
                                 autoSubmitMockedResponse: true,
                                 ...action.tool
                             });
@@ -534,14 +534,12 @@ export function WorkflowEditor({
     publishedWorkflowId,
     handleShowSelector,
     handleCloneVersion,
-    initialTestProfile,
 }: {
     dataSources: WithStringId<z.infer<typeof DataSource>>[];
     workflow: WithStringId<z.infer<typeof Workflow>>;
     publishedWorkflowId: string | null;
     handleShowSelector: () => void;
     handleCloneVersion: (workflowId: string) => void;
-    initialTestProfile: z.infer<typeof TestProfile>;
 }) {
     const [state, dispatch] = useReducer<Reducer<State, Action>>(reducer, {
         patches: [],
@@ -862,7 +860,6 @@ export function WorkflowEditor({
                     projectId={state.present.workflow.projectId}
                     workflow={state.present.workflow}
                     messageSubscriber={updateChatMessages}
-                    initialTestProfile={initialTestProfile}
                 />
                 {state.present.selection?.type === "agent" && <AgentConfig
                     key={state.present.selection.name}