Trace MCP

Instructions

Implementation Reference

• src/index.ts:331-355 (handler)

  Main handler for the 'trace_usage' MCP tool. Parses input using TraceUsageInput schema, calls traceConsumerUsage from src/trace/index.ts, and formats the result as JSON.
  case 'trace_usage': { const input = TraceUsageInput.parse(args); log(`Tracing usage in: ${input.rootDir}`); const usage = await traceConsumerUsage({ rootDir: input.rootDir, include: input.include, exclude: input.exclude, }); log(`Found ${usage.length} tool calls`); return { content: [ { type: 'text', text: JSON.stringify({ success: true, count: usage.length, usage, }, null, 2), }, ], }; }
• src/index.ts:51-55 (schema)

  Zod input schema validation for the trace_usage tool.
  const TraceUsageInput = z.object({ rootDir: z.string().describe('Root directory of consumer/client source code'), include: z.array(z.string()).optional().describe('Glob patterns to include'), exclude: z.array(z.string()).optional().describe('Glob patterns to exclude'), });
• src/index.ts:154-166 (registration)

  Registration of the 'trace_usage' tool in the ListTools response, including name, description, and inputSchema.
  { name: 'trace_usage', description: 'Trace how client code uses MCP tools. Finds callTool() invocations and tracks which properties are accessed on results.', inputSchema: { type: 'object', properties: { rootDir: { type: 'string', description: 'Root directory of consumer source code' }, include: { type: 'array', items: { type: 'string' }, description: 'Glob patterns to include' }, exclude: { type: 'array', items: { type: 'string' }, description: 'Glob patterns to exclude' }, }, required: ['rootDir'], }, },
• src/trace/index.ts:26-47 (helper)

  Core helper function traceConsumerUsage that delegates to the language-specific parser's traceUsage method.
  export async function traceConsumerUsage( options: TracerOptions ): Promise<ConsumerSchema[]> { // For backward compatibility, default to TypeScript const language = options.language || 'typescript'; // Get parser from registry if (!hasParser(language)) { throw new Error( `No parser available for language: ${language}. Make sure to call bootstrapLanguageParsers() at startup.` ); } const parser = getParser(language); return parser.traceUsage({ rootDir: options.rootDir, callPatterns: options.callPatterns, include: options.include, exclude: options.exclude, }); }