fix(mcp): hide server-beta-only tools from worker-runtime tools/list (closes #3064)

src/servers/mcp-server.ts

@@ -38,6 +38,7 @@ import {
   type SelectedRuntime,
   type ServerBetaRuntimeContext,
 } from '../services/hooks/runtime-selector.js';
+import { getAdvertisedMcpToolsForRuntime } from './mcp-tool-visibility.js';
 
 let mcpServerDirResolutionFailed = false;
 const mcpServerDir = (() => {
@@ -905,8 +906,9 @@ const server = new Server(
 );
 
 server.setRequestHandler(ListToolsRequestSchema, async () => {
+  const advertisedTools = getAdvertisedMcpToolsForRuntime(tools, selectRuntime());
   return {
-    tools: tools.map(tool => ({
+    tools: advertisedTools.map(tool => ({
       name: tool.name,
       description: tool.description,
       inputSchema: tool.inputSchema

src/servers/mcp-tool-visibility.ts

@@ -0,0 +1,29 @@
+import type { SelectedRuntime } from '../services/hooks/runtime-selector.js';
+import { logger } from '../utils/logger.js';
+
+export const SERVER_BETA_ONLY_TOOL_NAMES = [
+  'observation_add',
+  'observation_record_event',
+  'observation_search',
+  'observation_context',
+  'observation_generation_status',
+  'memory_add',
+  'memory_search',
+  'memory_context',
+] as const;
+
+const serverBetaOnlyToolNameSet = new Set<string>(SERVER_BETA_ONLY_TOOL_NAMES);
+
+export function getAdvertisedMcpToolsForRuntime<T extends { name: string }>(
+  allTools: readonly T[],
+  runtime: SelectedRuntime
+): T[] {
+  if (runtime === 'server-beta') {
+    return [...allTools];
+  }
+  logger.debug('SYSTEM', 'Filtering server-beta-only MCP tools from worker runtime advertisement', {
+    runtime,
+    hiddenToolCount: SERVER_BETA_ONLY_TOOL_NAMES.length,
+  });
+  return allTools.filter((tool) => !serverBetaOnlyToolNameSet.has(tool.name));
+}

tests/servers/mcp-runtime-tool-visibility.test.ts

@@ -0,0 +1,60 @@
+import { describe, it, expect } from 'bun:test';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import {
+  getAdvertisedMcpToolsForRuntime,
+  SERVER_BETA_ONLY_TOOL_NAMES,
+} from '../../src/servers/mcp-tool-visibility.js';
+
+const allTools = [
+  { name: 'search', description: '', inputSchema: {} },
+  { name: 'timeline', description: '', inputSchema: {} },
+  { name: 'get_observations', description: '', inputSchema: {} },
+  { name: 'observation_add', description: '', inputSchema: {} },
+  { name: 'observation_record_event', description: '', inputSchema: {} },
+  { name: 'observation_search', description: '', inputSchema: {} },
+  { name: 'observation_context', description: '', inputSchema: {} },
+  { name: 'observation_generation_status', description: '', inputSchema: {} },
+  { name: 'memory_add', description: '', inputSchema: {} },
+  { name: 'memory_search', description: '', inputSchema: {} },
+  { name: 'memory_context', description: '', inputSchema: {} },
+  { name: 'smart_search', description: '', inputSchema: {} },
+];
+
+describe('MCP runtime-aware tool visibility', () => {
+  it('base-fails/head-passes: worker hides server-beta-only tool names', () => {
+    const workerTools = getAdvertisedMcpToolsForRuntime(allTools, 'worker');
+    const names = new Set(workerTools.map(tool => tool.name));
+
+    for (const toolName of SERVER_BETA_ONLY_TOOL_NAMES) {
+      expect(names.has(toolName)).toBe(false);
+    }
+  });
+
+  it('base-fails/head-passes: server-beta keeps server-beta-only tool names', () => {
+    const serverBetaTools = getAdvertisedMcpToolsForRuntime(allTools, 'server-beta');
+    const names = new Set(serverBetaTools.map(tool => tool.name));
+
+    for (const toolName of SERVER_BETA_ONLY_TOOL_NAMES) {
+      expect(names.has(toolName)).toBe(true);
+    }
+  });
+
+  it('worker runtime still advertises core MCP worker tools', () => {
+    const workerTools = getAdvertisedMcpToolsForRuntime(allTools, 'worker');
+    const names = new Set(workerTools.map(tool => tool.name));
+
+    expect(names.has('search')).toBe(true);
+    expect(names.has('timeline')).toBe(true);
+    expect(names.has('get_observations')).toBe(true);
+    expect(names.has('smart_search')).toBe(true);
+  });
+
+  it('tools/list path references the helper so discovery is runtime-aware', () => {
+    const mcpServerPath = join(import.meta.dir, '..', '..', 'src', 'servers', 'mcp-server.ts');
+    const mcpServerSrc = readFileSync(mcpServerPath, 'utf-8');
+
+    expect(mcpServerSrc).toContain('getAdvertisedMcpToolsForRuntime(tools, selectRuntime())');
+    expect(mcpServerSrc).not.toContain('tools.map(tool => ({');
+  });
+});

tests/servers/mcp-tool-schemas.test.ts

@@ -1,6 +1,7 @@
 import { describe, it, expect } from 'bun:test';
+import { fileURLToPath } from 'node:url';
 
-const mcpServerPath = new URL('../../src/servers/mcp-server.ts', import.meta.url).pathname;
+const mcpServerPath = fileURLToPath(new URL('../../src/servers/mcp-server.ts', import.meta.url));
 
 describe('MCP tool inputSchema declarations', () => {
   let tools: any[];