Generate from a GraphQL schema

mcpgen reads a GraphQL schema and turns each root query and mutation field into an MCP tool. Field arguments become tool inputs; the GraphQL type maps to JSON Schema.

Supported

SDL (.graphql / .gql) — a schema definition document.
Introspection JSON — the result of an introspection query.
Parsed with the reference graphql package; no network calls during parse.

Generate


npx mcpgenx generate ./schema.graphql --out ./my-server


npx mcpgenx inspect ./schema.graphql

How fields map to tools

GraphQL	IR / generated tool
`Query.<field>`	a tool with `operation: query`, root `field`
`Mutation.<field>`	a tool with `operation: mutation`, root `field`
field arguments	tool input fields (`location: arg`)
argument / field types	JSON Schema on the input/output
field description	the tool description

The generated server builds and issues the GraphQL operation for you against the upstream endpoint (MCPGEN_API_BASE_URL), selecting the requested root field.

Subscriptions are not generated — MCP tools are request/response, so only Query and Mutation roots become tools.

Tips

Endpoint — set MCPGEN_API_BASE_URL to your GraphQL HTTP endpoint (e.g. https://api.example.com/graphql).
Auth — most GraphQL APIs use a bearer token; see Adding auth.
Selection sets — generated handlers request the fields described by the schema’s output type; trim or extend them in the generated handler if you need a narrower selection.