diff --git a/surfsense_mcp/src/surfsense_mcp/features/__init__.py b/surfsense_mcp/src/surfsense_mcp/features/__init__.py
new file mode 100644
index 000000000..0d3a683f6
--- /dev/null
+++ b/surfsense_mcp/src/surfsense_mcp/features/__init__.py
@@ -0,0 +1 @@
+"""Vertical slices: one folder per capability group exposed to MCP clients."""
diff --git a/surfsense_mcp/src/surfsense_mcp/features/workspaces/__init__.py b/surfsense_mcp/src/surfsense_mcp/features/workspaces/__init__.py
new file mode 100644
index 000000000..5f5372989
--- /dev/null
+++ b/surfsense_mcp/src/surfsense_mcp/features/workspaces/__init__.py
@@ -0,0 +1,82 @@
+"""Search-space selector: discover workspaces and choose the active one.
+
+A workspace (the product calls it a "search space") scopes every other tool.
+These two tools let a client list what's available and pick one by name, so the
+rest of the conversation needs no ids.
+"""
+
+from __future__ import annotations
+
+from mcp.server.fastmcp import FastMCP
+from mcp.types import ToolAnnotations
+
+from ...core.rendering import ResponseFormat, to_json
+from ...core.workspace_context import Workspace, WorkspaceContext
+
+_READ_ONLY = ToolAnnotations(
+    readOnlyHint=True, destructiveHint=False, idempotentHint=True, openWorldHint=False
+)
+
+
+def register(mcp: FastMCP, context: WorkspaceContext) -> None:
+    """Register the workspace selector tools on the server."""
+
+    @mcp.tool(
+        name="surfsense_list_workspaces",
+        annotations=_READ_ONLY,
+        structured_output=False,
+    )
+    async def list_workspaces(response_format: ResponseFormat = "markdown") -> str:
+        """List the SurfSense workspaces (search spaces) the account can access.
+
+        Use this to discover which workspaces exist before selecting one, or when
+        the user asks what search spaces they have. Returns each workspace's name,
+        id, description, ownership, and member count.
+        """
+        workspaces = await context.fetch_all()
+        if response_format == "json":
+            return to_json([_as_dict(w) for w in workspaces])
+        return _render_list(workspaces, active=context.active)
+
+    @mcp.tool(
+        name="surfsense_select_workspace",
+        annotations=_READ_ONLY,
+        structured_output=False,
+    )
+    async def select_workspace(workspace: str) -> str:
+        """Set the active workspace (search space) for later tools, by name or id.
+
+        Use this when the user says which search space to work in ("use my
+        Research space"). Accepts a workspace name or numeric id; matching is
+        case-insensitive and accepts a unique partial name. Once set, other tools
+        default to this workspace unless they are given a different one.
+        """
+        selected = await context.resolve(workspace)
+        return (
+            f"Active workspace is now '{selected.name}' (id {selected.id}). "
+            "Other tools will use it unless you pass a different 'workspace'."
+        )
+
+
+def _render_list(workspaces: list[Workspace], *, active: Workspace | None) -> str:
+    if not workspaces:
+        return "No accessible workspaces."
+    lines = ["# Workspaces", ""]
+    for workspace in workspaces:
+        marker = " — active" if active and active.id == workspace.id else ""
+        role = "owner" if workspace.is_owner else "member"
+        lines.append(f"- **{workspace.name}** (id {workspace.id}){marker}")
+        if workspace.description:
+            lines.append(f"  - {workspace.description}")
+        lines.append(f"  - {role}, {workspace.member_count} member(s)")
+    return "\n".join(lines)
+
+
+def _as_dict(workspace: Workspace) -> dict:
+    return {
+        "id": workspace.id,
+        "name": workspace.name,
+        "description": workspace.description,
+        "is_owner": workspace.is_owner,
+        "member_count": workspace.member_count,
+    }