Route-backed Tools

Eligible HTTP routes become MCP tools by default. The adapter inspects Elysia route metadata, builds JSON Schema inputs, and invokes every tool through the normal HTTP lifecycle.

Eligibility and naming

By default, GET, POST, PUT, PATCH, and DELETE routes are eligible. A route name is resolved from detail.operationId when present, then from the configured operationNameResolver.

mcp({
  methods: ['GET', 'POST'],
  operationNameResolver: ({ method, path, detail }) =>
    typeof detail?.operationId === 'string'
      ? detail.operationId
      : `${method.toLowerCase()}.${path}`
})

Use mcp: false or mcp: { expose: false } on a route to keep it out of the registry.

Select routes deliberately

mcp({
  allowedRoutes: [
    '/users/*',
    { method: 'GET', path: '/orders/:id' },
    /^\/public\//
  ],
  excludedRoutes: ['/admin/*']
})

An allowedRoutes array takes priority over excludedRoutes. The MCP endpoint itself and common OpenAPI, Swagger, and Scalar paths are excluded internally. Hidden routes stay excluded unless includeHiddenRoutes is enabled.

Input schema modes

The default envelope mode preserves the origin of every value:

{
  "params": { "id": "user_123" },
  "query": { "includeTeams": true },
  "body": { "displayName": "Ada" }
}

inputMode: 'flatten' merges compatible route inputs into one object. It is convenient for small APIs but can collide when params, query, and body reuse property names.

Override inferred schemas

mcp: {
  inputSchema: {
    type: 'object',
    properties: {
      params: {
        type: 'object',
        properties: { id: { type: 'string' } },
        required: ['id']
      }
    },
    required: ['params']
  },
  outputSchema: {
    type: 'object',
    properties: { id: { type: 'string' } },
    required: ['id']
  }
}

Route-level overrides win over inferred schemas. Use mapJsonSchema for a final, centralized transformation when a client has schema compatibility requirements.