Implemented project configuration to disable certain MCP tools to spare tokens with the initial schema in the context

Author: kecsap

README.md

@@ -358,6 +358,8 @@ When running as an MCP server, CodeGraph exposes these tools to Claude Code:
 | `codegraph_files` | Get indexed file structure (faster than filesystem scanning) |
 | `codegraph_status` | Check index health and statistics |
 
+You can hide specific MCP tools per-project via `.codegraph/config.json` (see Configuration below). Hidden tools are removed from `tools/list` and are treated as unknown if called directly.
+
 ---
 
 ## Library Usage
@@ -396,7 +398,10 @@ The `.codegraph/config.json` file controls indexing:
   "frameworks": [],
   "maxFileSize": 1048576,
   "extractDocstrings": true,
-  "trackCallSites": true
+  "trackCallSites": true,
+  "mcp": {
+    "disabledTools": ["codegraph_explore"]
+  }
 }
 ```
 
@@ -408,6 +413,13 @@ The `.codegraph/config.json` file controls indexing:
 | `maxFileSize` | Skip files larger than this (bytes) | `1048576` (1MB) |
 | `extractDocstrings` | Extract docstrings from code | `true` |
 | `trackCallSites` | Track call site locations | `true` |
+| `mcp.disabledTools` | MCP tool names to hide/disable for this project | `[]` |
+
+Example disabled tool names: `codegraph_explore`, `codegraph_context`, `codegraph_files`.
+
+Notes:
+- This setting is project-local only (no global override).
+- Unknown tool names are ignored (lenient behavior).
 
 ## Supported Languages
 

__tests__/foundation.test.ts

@@ -205,6 +205,31 @@ describe('CodeGraph Foundation', () => {
       const config = loadConfig(tempDir);
       expect(config.maxFileSize).toBe(999999);
     });
+
+    it('should persist MCP disabled tools config', () => {
+      const cg = CodeGraph.initSync(tempDir);
+
+      cg.updateConfig({
+        mcp: { disabledTools: ['codegraph_explore'] },
+      });
+
+      cg.close();
+
+      const config = loadConfig(tempDir);
+      expect(config.mcp?.disabledTools).toEqual(['codegraph_explore']);
+    });
+
+    it('should reject invalid mcp.disabledTools format', () => {
+      const cg = CodeGraph.initSync(tempDir);
+      cg.close();
+
+      const configPath = path.join(getCodeGraphDir(tempDir), 'config.json');
+      const raw = JSON.parse(fs.readFileSync(configPath, 'utf-8')) as Record<string, unknown>;
+      raw.mcp = { disabledTools: [123] };
+      fs.writeFileSync(configPath, JSON.stringify(raw, null, 2));
+
+      expect(() => loadConfig(tempDir)).toThrow(/Invalid configuration format/i);
+    });
   });
 
   describe('Directory Management', () => {

__tests__/security.test.ts

@@ -14,7 +14,7 @@ import * as path from 'path';
 import * as os from 'os';
 import { FileLock } from '../src/utils';
 import CodeGraph from '../src/index';
-import { ToolHandler, tools } from '../src/mcp/tools';
+import { ToolHandler, tools, filterToolsByConfig } from '../src/mcp/tools';
 import { shouldIncludeFile, scanDirectory } from '../src/extraction';
 import { shouldIncludeFile as configShouldInclude } from '../src/config';
 import { CodeGraphConfig, DEFAULT_CONFIG } from '../src/types';
@@ -265,6 +265,37 @@ describe('MCP Input Validation', () => {
     const result = await handler.execute('codegraph_search', { query: 'example', limit: -5 });
     expect(result.isError).toBeFalsy();
   });
+
+  it('should hide disabled tools from tool list', async () => {
+    const projectWithDisabled = createTempDir();
+    const srcDir = path.join(projectWithDisabled, 'src');
+    fs.mkdirSync(srcDir);
+    fs.writeFileSync(path.join(srcDir, 'x.ts'), 'export const x = 1;\n');
+
+    const disabledCg = CodeGraph.initSync(projectWithDisabled, {
+      config: {
+        include: ['**/*.ts'],
+        exclude: [],
+        mcp: { disabledTools: ['codegraph_explore'] },
+      },
+    });
+
+    try {
+      const disabledHandler = new ToolHandler(disabledCg);
+      const toolNames = disabledHandler.getTools().map(t => t.name);
+      expect(toolNames).not.toContain('codegraph_explore');
+    } finally {
+      disabledCg.close();
+      cleanupTempDir(projectWithDisabled);
+    }
+  });
+
+  it('should ignore unknown disabled tool names (lenient)', () => {
+    const filtered = filterToolsByConfig(tools, {
+      mcp: { disabledTools: ['not_a_real_tool_name'] },
+    });
+    expect(filtered).toHaveLength(tools.length);
+  });
 });
 
 describe('Atomic Writes', () => {

package-lock.json

@@ -68,6 +68,16 @@ export function validateConfig(config: unknown): config is CodeGraphConfig {
   if (typeof c.extractDocstrings !== 'boolean') return false;
   if (typeof c.trackCallSites !== 'boolean') return false;
 
+  // Validate MCP config if present
+  if (c.mcp !== undefined) {
+    if (typeof c.mcp !== 'object' || c.mcp === null) return false;
+    const mcp = c.mcp as Record<string, unknown>;
+    if (mcp.disabledTools !== undefined) {
+      if (!Array.isArray(mcp.disabledTools)) return false;
+      if (!mcp.disabledTools.every((t) => typeof t === 'string')) return false;
+    }
+  }
+
   // Validate include/exclude are string arrays
   if (!c.include.every((p) => typeof p === 'string')) return false;
   if (!c.exclude.every((p) => typeof p === 'string')) return false;
@@ -127,6 +137,9 @@ function mergeConfig(
     maxFileSize: overrides.maxFileSize ?? defaults.maxFileSize,
     extractDocstrings: overrides.extractDocstrings ?? defaults.extractDocstrings,
     trackCallSites: overrides.trackCallSites ?? defaults.trackCallSites,
+    mcp: {
+      disabledTools: overrides.mcp?.disabledTools ?? defaults.mcp?.disabledTools ?? [],
+    },
     customPatterns: overrides.customPatterns ?? defaults.customPatterns,
   };
 }

src/config.ts

@@ -18,7 +18,7 @@
 import * as path from 'path';
 import CodeGraph, { findNearestCodeGraphRoot } from '../index';
 import { StdioTransport, JsonRpcRequest, JsonRpcNotification, ErrorCodes } from './transport';
-import { tools, ToolHandler } from './tools';
+import { ToolHandler } from './tools';
 import { SERVER_INSTRUCTIONS } from './server-instructions';
 
 /**
@@ -314,9 +314,11 @@ export class MCPServer {
     const toolName = params.name;
     const toolArgs = params.arguments || {};
 
-    // Validate tool exists
-    const tool = tools.find(t => t.name === toolName);
-    if (!tool) {
+    // Validate tool is enabled for this project (disabled tools are hidden)
+    const projectPath = typeof toolArgs.projectPath === 'string'
+      ? toolArgs.projectPath
+      : undefined;
+    if (!this.toolHandler.isToolEnabled(toolName, projectPath)) {
       this.transport.sendError(
         request.id,
         ErrorCodes.InvalidParams,

src/mcp/index.ts

@@ -5,7 +5,7 @@
  */
 
 import CodeGraph, { findNearestCodeGraphRoot } from '../index';
-import type { Node, Edge, SearchResult, Subgraph, TaskContext, NodeKind } from '../types';
+import type { Node, Edge, SearchResult, Subgraph, TaskContext, NodeKind, CodeGraphConfig } from '../types';
 import { createHash } from 'crypto';
 import { writeFileSync, readFileSync, existsSync } from 'fs';
 import { clamp, validatePathWithinRoot } from '../utils';
@@ -286,6 +286,19 @@ export const tools: ToolDefinition[] = [
   },
 ];
 
+/**
+ * Filter tool definitions by project MCP config.
+ * Unknown disabled tool names are ignored (lenient behavior).
+ */
+export function filterToolsByConfig(
+  allTools: ToolDefinition[],
+  config?: Pick<CodeGraphConfig, 'mcp'> | null
+): ToolDefinition[] {
+  const disabled = new Set(config?.mcp?.disabledTools ?? []);
+  if (disabled.size === 0) return allTools;
+  return allTools.filter(tool => !disabled.has(tool.name));
+}
+
 /**
  * Tool handler that executes tools against a CodeGraph instance
  *
@@ -317,14 +330,25 @@ export class ToolHandler {
    * The codegraph_explore tool description includes a budget recommendation
    * scaled to the number of indexed files.
    */
-  getTools(): ToolDefinition[] {
-    if (!this.cg) return tools;
+  getTools(projectPath?: string): ToolDefinition[] {
+    let baseTools = tools;
+
+    try {
+      const cg = projectPath ? this.getCodeGraph(projectPath) : this.cg;
+      if (cg) {
+        baseTools = filterToolsByConfig(baseTools, cg.getConfig());
+      }
+    } catch {
+      // If project resolution fails here, keep fallback behavior and expose all tools.
+    }
+
+    if (!this.cg) return baseTools;
 
     try {
       const stats = this.cg.getStats();
       const budget = getExploreBudget(stats.fileCount);
 
-      return tools.map(tool => {
+      return baseTools.map(tool => {
         if (tool.name === 'codegraph_explore') {
           return {
             ...tool,
@@ -334,10 +358,17 @@ export class ToolHandler {
         return tool;
       });
     } catch {
-      return tools;
+      return baseTools;
     }
   }
 
+  /**
+   * Check whether a tool is enabled for the target project.
+   */
+  isToolEnabled(toolName: string, projectPath?: string): boolean {
+    return this.getTools(projectPath).some(tool => tool.name === toolName);
+  }
+
   /**
    * Get CodeGraph instance for a project
    *

src/mcp/tools.ts

@@ -478,6 +478,12 @@ export interface CodeGraphConfig {
   /** Whether to track call sites */
   trackCallSites: boolean;
 
+  /** MCP server configuration */
+  mcp?: {
+    /** Tool names to hide/disable from MCP clients */
+    disabledTools?: string[];
+  };
+
   /** Custom symbol patterns to extract */
   customPatterns?: {
     /** Name for this pattern group */
@@ -693,6 +699,9 @@ export const DEFAULT_CONFIG: CodeGraphConfig = {
   maxFileSize: 1024 * 1024, // 1MB
   extractDocstrings: true,
   trackCallSites: true,
+  mcp: {
+    disabledTools: [],
+  },
 };
 
 // =============================================================================