diff --git a/docs-site/content/docs/cli-reference/ktx-mongo-query.mdx b/docs-site/content/docs/cli-reference/ktx-mongo-query.mdx
index 86f2378d..a8aaf48b 100644
--- a/docs-site/content/docs/cli-reference/ktx-mongo-query.mdx
+++ b/docs-site/content/docs/cli-reference/ktx-mongo-query.mdx
@@ -26,7 +26,7 @@ ktx mongo-query '<pipeline-json>' --connection <id> --collection <name> [options
 | `--collection <name>` | Collection to query. Required. | - |
 | `--database <name>` | Database name. | Connection's first configured database |
 | `--limit <n>` | Maximum documents to return. Must be between `1` and `10000`. | `1000` |
-| `--output <mode>` | Output mode: `pretty`, `plain` (TSV), or `json`. | `pretty` |
+| `--output <mode>` | Output mode: `pretty`, `plain` (TSV), or `json`. | `pretty` on a terminal, `plain` when piped or in CI (override with `KTX_OUTPUT`) |
 | `--json` | Shortcut for `--output=json` (overrides `--output`). | `false` |
 
 ## Examples
diff --git a/docs-site/content/docs/cli-reference/ktx-sql.mdx b/docs-site/content/docs/cli-reference/ktx-sql.mdx
index d78864e2..aa0ef959 100644
--- a/docs-site/content/docs/cli-reference/ktx-sql.mdx
+++ b/docs-site/content/docs/cli-reference/ktx-sql.mdx
@@ -24,7 +24,7 @@ JSON.
 |------|-------------|---------|
 | `-c`, `--connection <id>` | **ktx** database connection id. Required. | - |
 | `--max-rows <n>` | Maximum rows to return. Must be between `1` and `10000`. | `1000` |
-| `--output <mode>` | Output mode: `pretty`, `plain` (TSV), or `json`. | `pretty` |
+| `--output <mode>` | Output mode: `pretty`, `plain` (TSV), or `json`. | `pretty` on a terminal, `plain` when piped or in CI (override with `KTX_OUTPUT`) |
 | `--json` | Shortcut for `--output=json` (overrides `--output`). | `false` |
 
 ## Examples
diff --git a/packages/cli/src/commands/mongo-query-commands.ts b/packages/cli/src/commands/mongo-query-commands.ts
index 30a6bc21..206c5df9 100644
--- a/packages/cli/src/commands/mongo-query-commands.ts
+++ b/packages/cli/src/commands/mongo-query-commands.ts
@@ -7,7 +7,8 @@ profileMark('module:commands/mongo-query-commands');
 const DEFAULT_LIMIT = 1000;
 const LIMIT_CAP = 10_000;
 
-function parseLimitOption(value: string): number {
+/** @internal exported only for unit testing */
+export function parseLimitOption(value: string): number {
   const parsed = Number(value);
   if (!Number.isInteger(parsed) || parsed < 1 || parsed > LIMIT_CAP) {
     throw new InvalidArgumentError(`must be an integer between 1 and ${LIMIT_CAP}`);
diff --git a/packages/cli/src/connectors/mongodb/connector.ts b/packages/cli/src/connectors/mongodb/connector.ts
index d6d185c8..6d45ed69 100644
--- a/packages/cli/src/connectors/mongodb/connector.ts
+++ b/packages/cli/src/connectors/mongodb/connector.ts
@@ -6,6 +6,8 @@ import {
   type KtxColumnSampleInput,
   type KtxColumnSampleResult,
   type KtxConnectorTestResult,
+  type KtxMongoQueryInput,
+  type KtxMongoQueryResult,
   type KtxScanConnector,
   type KtxScanContext,
   type KtxScanInput,
@@ -39,20 +41,6 @@ export interface KtxMongoListedCollection {
   type?: string;
 }
 
-export interface KtxMongoQueryInput {
-  connectionId: string;
-  collection: string;
-  database?: string;
-  pipeline: Record<string, unknown>[];
-  limit: number;
-}
-
-export interface KtxMongoQueryResult {
-  headers: string[];
-  rows: unknown[][];
-  rowCount: number;
-}
-
 interface KtxMongoFindOptions {
   sort: Record<string, 1 | -1>;
   limit: number;
@@ -67,7 +55,7 @@ export interface KtxMongoClient {
   aggregate(
     databaseName: string,
     collectionName: string,
-    pipeline: Record<string, unknown>[],
+    pipeline: readonly Record<string, unknown>[],
     options: { limit: number },
   ): Promise<KtxMongoDocument[]>;
   ping(databaseName: string): Promise<void>;
@@ -129,7 +117,7 @@ class DefaultMongoClient implements KtxMongoClient {
   async aggregate(
     databaseName: string,
     collectionName: string,
-    pipeline: Record<string, unknown>[],
+    pipeline: readonly Record<string, unknown>[],
     options: { limit: number },
   ): Promise<KtxMongoDocument[]> {
     const client = await this.connectedClient();
@@ -223,7 +211,7 @@ function unionDocumentKeys(documents: readonly KtxMongoDocument[]): string[] {
 }
 
 // MongoDB aggregation write stages ($out/$merge) persist results; mongo_query is read-only.
-function assertReadOnlyPipeline(pipeline: Record<string, unknown>[]): void {
+function assertReadOnlyPipeline(pipeline: readonly Record<string, unknown>[]): void {
   for (const stage of pipeline) {
     if ('$out' in stage || '$merge' in stage) {
       throw new Error('mongo_query pipelines must be read-only; $out and $merge stages are not allowed.');
diff --git a/packages/cli/src/context/mcp/local-project-ports.ts b/packages/cli/src/context/mcp/local-project-ports.ts
index 43901685..d1cc28e4 100644
--- a/packages/cli/src/context/mcp/local-project-ports.ts
+++ b/packages/cli/src/context/mcp/local-project-ports.ts
@@ -15,7 +15,6 @@ import { KtxDaemonComputeError, type KtxSemanticLayerComputePort } from '../../c
 import type { KtxLocalProject } from '../../context/project/project.js';
 import { createKtxEntityDetailsService } from '../../context/scan/entity-details.js';
 import type { LocalScanMcpOptions } from '../../context/scan/local-scan.js';
-import type { KtxScanConnector } from '../../context/scan/types.js';
 import { createKtxDiscoverDataService } from '../../context/search/discover.js';
 import { sqlAnalysisDialectForDriver } from '../../context/sql-analysis/dialect.js';
 import type { SqlAnalysisPort } from '../../context/sql-analysis/ports.js';
@@ -26,7 +25,7 @@ import { assertSafeConnectionId } from '../../context/sl/source-files.js';
 import { assertConfiguredConnectionId } from '../../context/connections/configured-connections.js';
 import { readLocalKnowledgePage, searchLocalKnowledgePages } from '../wiki/local-knowledge.js';
 import { runMongoQuery } from './mongo-query-runner.js';
-import type { KtxMcpContextPorts, KtxMcpProgressCallback, KtxMongoQueryResponse, KtxSqlExecutionResponse } from './types.js';
+import type { KtxMcpContextPorts, KtxMcpProgressCallback, KtxSqlExecutionResponse } from './types.js';
 
 interface CreateLocalProjectMcpContextPortsOptions {
   semanticLayerCompute?: KtxSemanticLayerComputePort;
@@ -62,13 +61,6 @@ function projectHasMongoConnection(project: KtxLocalProject): boolean {
   );
 }
 
-async function executeMongoQuery(
-  createConnector: (connectionId: string) => Promise<KtxScanConnector> | KtxScanConnector,
-  input: { connectionId: string; collection: string; database?: string; pipeline: Record<string, unknown>[]; limit: number },
-): Promise<KtxMongoQueryResponse> {
-  return runMongoQuery(createConnector, input);
-}
-
 async function executeValidatedReadOnlySql(
   project: KtxLocalProject,
   options: CreateLocalProjectMcpContextPortsOptions,
@@ -259,7 +251,7 @@ export function createLocalProjectMcpContextPorts(
     ports.mongoQuery = {
       async execute(input) {
         try {
-          return await executeMongoQuery(mongoCreateConnector, input);
+          return await runMongoQuery(mongoCreateConnector, input);
         } catch (error) {
           throwClassifiedQueryError(error);
         }
diff --git a/packages/cli/src/context/mcp/mongo-query-runner.ts b/packages/cli/src/context/mcp/mongo-query-runner.ts
index fdd0b082..65136cd8 100644
--- a/packages/cli/src/context/mcp/mongo-query-runner.ts
+++ b/packages/cli/src/context/mcp/mongo-query-runner.ts
@@ -1,34 +1,22 @@
-import type { KtxMongoDbScanConnector, KtxMongoQueryResult } from '../../connectors/mongodb/connector.js';
 import { KtxExpectedError } from '../../errors.js';
 import { assertSafeConnectionId } from '../sl/source-files.js';
-import type { KtxScanConnector } from '../scan/types.js';
-
-export interface KtxMongoQueryRequest {
-  connectionId: string;
-  collection: string;
-  database?: string;
-  pipeline: Record<string, unknown>[];
-  limit: number;
-}
+import type { KtxMongoQueryInput, KtxMongoQueryResult, KtxScanConnector } from '../scan/types.js';
 
 /** Single Mongo-read execution seam: resolve the connector, guard the driver, run the pipeline. */
 export async function runMongoQuery(
   createConnector: (connectionId: string) => Promise<KtxScanConnector> | KtxScanConnector,
-  input: KtxMongoQueryRequest,
+  input: KtxMongoQueryInput,
 ): Promise<KtxMongoQueryResult> {
   const connectionId = assertSafeConnectionId(input.connectionId);
   let connector: KtxScanConnector | null = null;
   try {
     connector = await createConnector(connectionId);
-    if (connector.driver !== 'mongodb') {
+    if (connector.driver !== 'mongodb' || typeof connector.executeQuery !== 'function') {
       throw new KtxExpectedError(
         `Connection "${connectionId}" driver "${connector.driver}" is not a MongoDB connection; mongo_query serves mongodb connections only.`,
       );
     }
-    return await (connector as unknown as KtxMongoDbScanConnector).executeQuery(
-      { connectionId, collection: input.collection, database: input.database, pipeline: input.pipeline, limit: input.limit },
-      { runId: 'mongo-query' },
-    );
+    return await connector.executeQuery({ ...input, connectionId }, { runId: 'mongo-query' });
   } finally {
     await connector?.cleanup?.();
   }
diff --git a/packages/cli/src/context/mcp/types.ts b/packages/cli/src/context/mcp/types.ts
index 4ef12272..f05c49b4 100644
--- a/packages/cli/src/context/mcp/types.ts
+++ b/packages/cli/src/context/mcp/types.ts
@@ -5,7 +5,7 @@ import type { KtxEntityDetailsInput, KtxEntityDetailsResponse } from '../scan/en
 import type { KtxDiscoverDataInput, KtxDiscoverDataResponse } from '../../context/search/discover.js';
 import type { KtxDictionarySearchInput, KtxDictionarySearchResponse } from '../../context/sl/dictionary-search.js';
 import type { SemanticLayerQueryInput } from '../../context/sl/types.js';
-import type { KtxMongoQueryResult } from '../../connectors/mongodb/connector.js';
+import type { KtxMongoQueryInput, KtxMongoQueryResult } from '../scan/types.js';
 import type { WikiSearchLaneSummary, WikiSearchMatchReason } from '../../context/wiki/types.js';
 
 interface KtxMcpTextContent {
@@ -181,14 +181,9 @@ export interface KtxSqlExecutionMcpPort {
   ): Promise<KtxSqlExecutionResponse>;
 }
 
-export type KtxMongoQueryResponse = KtxMongoQueryResult;
-
 /** @internal */
 export interface KtxMongoQueryMcpPort {
-  execute(
-    input: { connectionId: string; collection: string; database?: string; pipeline: Record<string, unknown>[]; limit: number },
-    options?: { onProgress?: KtxMcpProgressCallback },
-  ): Promise<KtxMongoQueryResponse>;
+  execute(input: KtxMongoQueryInput, options?: { onProgress?: KtxMcpProgressCallback }): Promise<KtxMongoQueryResult>;
 }
 
 /** @internal */
diff --git a/packages/cli/src/context/scan/types.ts b/packages/cli/src/context/scan/types.ts
index bf72558c..3d39307b 100644
--- a/packages/cli/src/context/scan/types.ts
+++ b/packages/cli/src/context/scan/types.ts
@@ -293,6 +293,20 @@ export interface KtxReadOnlyQueryInput {
   maxRows?: number;
 }
 
+export interface KtxMongoQueryInput {
+  connectionId: string;
+  collection: string;
+  database?: string;
+  pipeline: readonly Record<string, unknown>[];
+  limit: number;
+}
+
+export interface KtxMongoQueryResult {
+  headers: string[];
+  rows: unknown[][];
+  rowCount: number;
+}
+
 export interface KtxQueryResult {
   headers: string[];
   headerTypes?: string[];
@@ -346,6 +360,7 @@ export interface KtxScanConnector {
   sampleTable?(input: KtxTableSampleInput, ctx: KtxScanContext): Promise<KtxTableSampleResult>;
   columnStats?(input: KtxColumnStatsInput, ctx: KtxScanContext): Promise<KtxColumnStatsResult | null>;
   executeReadOnly?(input: KtxReadOnlyQueryInput, ctx: KtxScanContext): Promise<KtxQueryResult>;
+  executeQuery?(input: KtxMongoQueryInput, ctx: KtxScanContext): Promise<KtxMongoQueryResult>;
   cleanup?(): Promise<void>;
 }
 
diff --git a/packages/cli/src/mongo-query.ts b/packages/cli/src/mongo-query.ts
index f529df88..17b1e33e 100644
--- a/packages/cli/src/mongo-query.ts
+++ b/packages/cli/src/mongo-query.ts
@@ -1,6 +1,7 @@
 import { runMongoQuery } from './context/mcp/mongo-query-runner.js';
 import { resolveConfiguredConnection } from './context/connections/resolve-connection.js';
 import { loadKtxProject, type KtxLocalProject } from './context/project/project.js';
+import type { KtxMongoQueryInput } from './context/scan/types.js';
 import type { KtxCliIo } from './cli-runtime.js';
 import { type KtxOutputMode, resolveOutputMode } from './io/mode.js';
 import { type KtxResultTable, printResultTable } from './io/result-table.js';
@@ -13,13 +14,8 @@ import { scrubErrorClass } from './telemetry/scrubber.js';
 
 profileMark('module:mongo-query');
 
-export type KtxMongoQueryArgs = {
+export type KtxMongoQueryArgs = KtxMongoQueryInput & {
   projectDir: string;
-  connectionId: string;
-  collection: string;
-  database?: string;
-  pipeline: Record<string, unknown>[];
-  limit: number;
   output?: KtxOutputMode;
   json?: boolean;
   cliVersion: string;
diff --git a/packages/cli/test/commands/mongo-query-commands.test.ts b/packages/cli/test/commands/mongo-query-commands.test.ts
index 61199754..c04d988d 100644
--- a/packages/cli/test/commands/mongo-query-commands.test.ts
+++ b/packages/cli/test/commands/mongo-query-commands.test.ts
@@ -1,6 +1,6 @@
 import { InvalidArgumentError } from '@commander-js/extra-typings';
 import { describe, expect, it } from 'vitest';
-import { parsePipelineArgument } from '../../src/commands/mongo-query-commands.js';
+import { parseLimitOption, parsePipelineArgument } from '../../src/commands/mongo-query-commands.js';
 
 describe('parsePipelineArgument', () => {
   it('parses a valid JSON array of pipeline-stage objects', () => {
@@ -34,3 +34,26 @@ describe('parsePipelineArgument', () => {
     expect(() => parsePipelineArgument('[null]')).toThrow(InvalidArgumentError);
   });
 });
+
+describe('parseLimitOption', () => {
+  it('accepts the boundary values 1 and 10000', () => {
+    expect(parseLimitOption('1')).toBe(1);
+    expect(parseLimitOption('10000')).toBe(10000);
+  });
+
+  it('rejects a non-numeric value', () => {
+    expect(() => parseLimitOption('abc')).toThrow(InvalidArgumentError);
+  });
+
+  it('rejects a non-integer value', () => {
+    expect(() => parseLimitOption('1.5')).toThrow(InvalidArgumentError);
+  });
+
+  it('rejects a value below 1', () => {
+    expect(() => parseLimitOption('0')).toThrow(InvalidArgumentError);
+  });
+
+  it('rejects a value above the cap', () => {
+    expect(() => parseLimitOption('10001')).toThrow(InvalidArgumentError);
+  });
+});
diff --git a/packages/cli/test/connectors/mongodb/connector.test.ts b/packages/cli/test/connectors/mongodb/connector.test.ts
index 7089ee21..e46d4bc2 100644
--- a/packages/cli/test/connectors/mongodb/connector.test.ts
+++ b/packages/cli/test/connectors/mongodb/connector.test.ts
@@ -295,4 +295,23 @@ describe('KtxMongoDbScanConnector.executeQuery', () => {
       ),
     ).rejects.toThrow(/must be read-only/);
   });
+
+  it('runs against the requested database when input.database is given', async () => {
+    const { factory, client } = fakeClientFactory();
+    await connector(baseConnection, factory).executeQuery(
+      { connectionId: 'mongo-prod', collection: 'orders', database: 'analytics', pipeline: [], limit: 5 },
+      { runId: 't' },
+    );
+    expect(client.aggregate).toHaveBeenCalledWith('analytics', 'orders', [], { limit: 5 });
+  });
+
+  it('returns an empty result with no headers when the pipeline matches no documents', async () => {
+    const { factory, client } = fakeClientFactory();
+    (client.aggregate as ReturnType<typeof vi.fn>).mockResolvedValueOnce([]);
+    const result = await connector(baseConnection, factory).executeQuery(
+      { connectionId: 'mongo-prod', collection: 'users', pipeline: [{ $match: { age: { $gte: 999 } } }], limit: 50 },
+      { runId: 't' },
+    );
+    expect(result).toEqual({ headers: [], rows: [], rowCount: 0 });
+  });
 });
diff --git a/packages/cli/test/context/mcp/server.test.ts b/packages/cli/test/context/mcp/server.test.ts
index 69091aab..43f9b320 100644
--- a/packages/cli/test/context/mcp/server.test.ts
+++ b/packages/cli/test/context/mcp/server.test.ts
@@ -22,12 +22,12 @@ import type {
   KtxMcpContextPorts,
   KtxMcpToolHandlerContext,
   KtxMongoQueryMcpPort,
-  KtxMongoQueryResponse,
   KtxSemanticLayerMcpPort,
   KtxSqlExecutionMcpPort,
   KtxSqlExecutionResponse,
   MemoryIngestPort,
 } from '../../../src/context/mcp/types.js';
+import type { KtxMongoQueryResult } from '../../../src/context/scan/types.js';
 
 const reportExceptionMock = vi.hoisted(() => vi.fn(async () => {}));
 
@@ -499,7 +499,7 @@ describe('createKtxMcpServer', () => {
 
   it('registers mongo_query when the host provides a MongoDB query port', async () => {
     const fake = makeFakeServer();
-    const response: KtxMongoQueryResponse = {
+    const response: KtxMongoQueryResult = {
       headers: ['_id', 'city'],
       rows: [
         ['a1', 'Indianapolis'],
diff --git a/packages/cli/test/io/result-table.test.ts b/packages/cli/test/io/result-table.test.ts
index 39508d37..9129265e 100644
--- a/packages/cli/test/io/result-table.test.ts
+++ b/packages/cli/test/io/result-table.test.ts
@@ -18,6 +18,7 @@ describe('formatValue', () => {
     expect(formatValue('x')).toBe('x');
     expect(formatValue(42)).toBe('42');
     expect(formatValue(true)).toBe('true');
+    expect(formatValue(10n)).toBe('10');
     expect(formatValue({ a: 1 })).toBe(JSON.stringify({ a: 1 }));
   });
 });
@@ -37,10 +38,33 @@ describe('printResultTable', () => {
     expect(out()).toBe('_id\tcity\na1\tNY\n');
   });
 
-  it('pretty mode prints a header rule and a row count', () => {
+  it('pretty mode prints a header rule and a singular row count', () => {
     const { io, out } = captureIo();
     printResultTable(table, 'pretty', io);
     expect(out()).toContain('_id');
-    expect(out()).toContain('1 row');
+    expect(out()).toContain('1 row\n');
+  });
+
+  it('pretty mode aligns multiple rows and pluralizes the row count', () => {
+    const { io, out } = captureIo();
+    const multi = {
+      connectionId: 'mongo',
+      headers: ['id', 'city'],
+      rows: [
+        ['1', 'NY'],
+        ['1000', 'Indianapolis'],
+      ],
+      rowCount: 2,
+    };
+    printResultTable(multi, 'pretty', io);
+    // Column widened to the longest cell ("1000"), so "1" is right-padded to 4 chars.
+    expect(out()).toContain('1     NY');
+    expect(out()).toContain('2 rows\n');
+  });
+
+  it('pretty mode omits the header rule when there are no headers', () => {
+    const { io, out } = captureIo();
+    printResultTable({ connectionId: 'mongo', headers: [], rows: [], rowCount: 0 }, 'pretty', io);
+    expect(out()).toBe('\n0 rows\n');
   });
 });
diff --git a/packages/cli/test/mongo-query.test.ts b/packages/cli/test/mongo-query.test.ts
index be1265ca..5b7d17bb 100644
--- a/packages/cli/test/mongo-query.test.ts
+++ b/packages/cli/test/mongo-query.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it, vi } from 'vitest';
+import { afterEach, describe, expect, it, vi } from 'vitest';
 import { runKtxMongoQuery } from '../src/mongo-query.js';
 import { KtxMongoDbScanConnector } from '../src/connectors/mongodb/connector.js';
 import type { KtxCliIo } from '../src/cli-runtime.js';
@@ -67,3 +67,36 @@ describe('runKtxMongoQuery', () => {
     expect(err().length).toBeGreaterThan(0);
   });
 });
+
+describe('runKtxMongoQuery telemetry', () => {
+  afterEach(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it('emits mongo_query_completed with outcome ok and the pipeline stage count on success', async () => {
+    vi.stubEnv('KTX_TELEMETRY_DEBUG', '1');
+    vi.stubEnv('CI', '');
+    const { io, err } = captureIo();
+    const code = await runKtxMongoQuery({ ...baseArgs, output: 'plain' }, io, {
+      loadProject: async () => project,
+      createScanConnector: (async () => mongoConnector()) as never,
+    });
+    expect(code).toBe(0);
+    expect(err()).toContain('"event":"mongo_query_completed"');
+    expect(err()).toContain('"outcome":"ok"');
+    expect(err()).toContain('"stageCount":1');
+  });
+
+  it('emits mongo_query_completed with outcome error on failure', async () => {
+    vi.stubEnv('KTX_TELEMETRY_DEBUG', '1');
+    vi.stubEnv('CI', '');
+    const { io, err } = captureIo();
+    const code = await runKtxMongoQuery({ ...baseArgs, connectionId: 'nope' }, io, {
+      loadProject: async () => project,
+      createScanConnector: (async () => mongoConnector()) as never,
+    });
+    expect(code).toBe(1);
+    expect(err()).toContain('"event":"mongo_query_completed"');
+    expect(err()).toContain('"outcome":"error"');
+  });
+});