Trace MCP

Instructions

Implementation Reference

• src/tools/scaffold.ts:84-130 (handler)

  Core handler function that implements the scaffold_producer tool logic: infers Zod schema from consumer arguments and generates MCP server.tool() code stub, optionally with a handler.
  export function scaffoldProducerFromConsumer( consumer: ConsumerSchema, options: { includeHandler?: boolean } = {} ): ScaffoldResult { const { includeHandler = true } = options; const toolName = consumer.toolName; const args = consumer.argumentsProvided; // Infer types from argument values (basic inference) const inferredSchema = inferSchemaFromArgs(args); const code = ` import { z } from 'zod'; // Tool: ${toolName} // Scaffolded from consumer at ${consumer.callSite.file}:${consumer.callSite.line} // @trace-contract PRODUCER (scaffolded) server.tool( '${toolName}', 'TODO: Add description', { ${Object.entries(inferredSchema) .map(([key, type]) => ` ${key}: ${type},`) .join('\n')} }, ${includeHandler ? ` async (args) => { // TODO: Implement handler // Consumer expects these properties: ${consumer.expectedProperties.join(', ')} return { content: [{ type: 'text', text: JSON.stringify({ ${consumer.expectedProperties.map(p => ` ${p}: null, // TODO`).join('\n')} }) }] }; }` : ' async (args) => { /* TODO */ }'} ); `.trim(); return { code, suggestedFilename: `${toKebabCase(toolName)}-tool.ts`, example: `// This tool is called by:\n// ${consumer.callSite.file}:${consumer.callSite.line}`, }; }
• src/index.ts:444-476 (handler)

  MCP server dispatch handler for 'scaffold_producer' tool call: validates input, traces consumer usage, invokes core scaffoldProducerFromConsumer, and formats response.
  case 'scaffold_producer': { const input = ScaffoldProducerInput.parse(args); log(`Scaffolding producer for tool: ${input.toolName}`); // Trace consumer usage to find the requested tool const consumers = await traceConsumerUsage({ rootDir: input.consumerDir }); const consumer = consumers.find(c => c.toolName === input.toolName); if (!consumer) { throw new Error(`Tool "${input.toolName}" not found in consumer code at ${input.consumerDir}`); } const result = scaffoldProducerFromConsumer(consumer, { includeHandler: input.includeHandler ?? true, }); log(`Generated producer schema stub`); return { content: [ { type: 'text', text: JSON.stringify({ success: true, toolName: input.toolName, suggestedFilename: result.suggestedFilename, code: result.code, example: result.example, }, null, 2), }, ], }; }
• src/index.ts:81-85 (schema)

  Zod input schema for validating arguments to the scaffold_producer tool.
  const ScaffoldProducerInput = z.object({ consumerDir: z.string().describe('Path to consumer source directory'), toolName: z.string().describe('Name of the tool to scaffold producer for'), includeHandler: z.boolean().optional().describe('Include handler stub (default: true)'), });
• src/index.ts:208-220 (registration)

  Tool registration metadata (name, description, inputSchema) returned by listTools request.
  { name: 'scaffold_producer', description: 'Generate producer schema stub from consumer usage. Creates MCP tool definition based on how client code calls it.', inputSchema: { type: 'object', properties: { consumerDir: { type: 'string', description: 'Path to consumer source directory' }, toolName: { type: 'string', description: 'Name of the tool to scaffold producer for' }, includeHandler: { type: 'boolean', description: 'Include handler stub' }, }, required: ['consumerDir', 'toolName'], }, },
• src/tools/index.ts:14-18 (registration)

  Re-export of scaffoldProducerFromConsumer function, imported into main index.ts for tool handler.
  scaffoldConsumerFromProducer, scaffoldProducerFromConsumer, type ScaffoldOptions, type ScaffoldResult, } from './scaffold.js';