Un servidor MCP (Model Context Protocol) genérico que conecta cualquier API GraphQL con Claude Code. Realiza una introspección de tu esquema GraphQL y expone cada consulta y mutación como una herramienta individual, permitiendo que Claude interactúe directamente con tu API.
Al iniciarse, el servidor:
Busca un archivo schema-introspection.json en el directorio de trabajo (rápido, sin llamadas de red)
Si no lo encuentra, ejecuta una introspección en tiempo real contra GRAPHQL_INTROSPECTION_URL
Registra una herramienta por consulta (query__<name>) y una por mutación (mutation__<name>)
Registra siempre una herramienta de respaldo genérica execute_graphql y una herramienta de exploración get_type_details
Related MCP server: GraphQL MCP Server
Node.js >= 18
npm install -g mcp-graphql-bridgegit clone https://github.com/murilopereira/mcp-graphql-bridge.git
cd mcp-graphql-bridge
npm install
npm run buildVariable | Requerida | Descripción |
| Sí | Endpoint utilizado para consultas y mutaciones |
| Sí | Endpoint utilizado para la introspección del esquema (puede ser el mismo que el anterior) |
| Sí | Token Bearer para autenticación |
Puedes configurarlas en un archivo .env en la raíz del proyecto:
GRAPHQL_API_URL=https://your-api.example.com/graphql
GRAPHQL_INTROSPECTION_URL=https://your-api.example.com/graphql
GRAPHQL_TOKEN=your-bearer-tokenO pasarlas directamente mediante el comando claude mcp add (ver más abajo).
Por defecto, el servidor realiza la introspección de tu esquema en tiempo real al iniciarse; no se necesita ningún archivo. Utiliza este paso solo si tu API tiene la introspección deshabilitada en producción, o si deseas tiempos de inicio más rápidos:
curl -s -X POST https://your-api.example.com/graphql \
-H "Content-Type: application/json" \
-H "Authorization: Bearer your-bearer-token" \
-d '{"query":"{ __schema { queryType { fields { name description args { name description defaultValue type { kind name ofType { kind name ofType { kind name ofType { kind name } } } } } type { kind name ofType { kind name ofType { kind name } } } } } mutationType { fields { name description args { name description defaultValue type { kind name ofType { kind name ofType { kind name ofType { kind name } } } } } type { kind name ofType { kind name ofType { kind name } } } } } } }"}' \
> schema-introspection.jsonSi se instaló desde npm:
claude mcp add --transport stdio \
--env GRAPHQL_API_URL=https://your-api.example.com/graphql \
--env GRAPHQL_INTROSPECTION_URL=https://your-api.example.com/graphql \
--env GRAPHQL_TOKEN=your-bearer-token \
graphql-bridge -- mcp-graphql-bridgeSi se clonó desde el código fuente:
claude mcp add --transport stdio \
--env GRAPHQL_API_URL=https://your-api.example.com/graphql \
--env GRAPHQL_INTROSPECTION_URL=https://your-api.example.com/graphql \
--env GRAPHQL_TOKEN=your-bearer-token \
graphql-bridge -- node /absolute/path/to/mcp-graphql-bridge/dist/index.jsImportante: Asegúrate de usar
mcp-graphql-bridge/dist/index.js(la salida compilada), nomcp-graphql-bridge/index.js. El código fuente en TypeScript debe compilarse primero connpm run build, y el punto de entrada se encuentra en la carpetadist/.
.mcp.json)claude mcp add --transport stdio --scope project \
--env GRAPHQL_API_URL=https://your-api.example.com/graphql \
--env GRAPHQL_INTROSPECTION_URL=https://your-api.example.com/graphql \
--env GRAPHQL_TOKEN=your-bearer-token \
graphql-bridge -- mcp-graphql-bridgeNota: Usa rutas absolutas. Todas las banderas
--envy--transportdeben ir antes del nombre del servidor.
claude mcp listLuego, en una sesión de Claude Code, ejecuta /mcp para ver los servidores y herramientas disponibles.
Herramienta | Descripción |
| Una herramienta por campo de consulta GraphQL |
| Una herramienta por campo de mutación GraphQL |
| Respaldo genérico: ejecuta cualquier consulta o mutación |
| Explora los campos de un tipo GraphQL específico |
Todas las herramientas por operación aceptan un argumento especial __fields donde puedes proporcionar un conjunto de selección GraphQL personalizado (p. ej., { id name status }). Si se omite, solo se devuelven los campos escalares.
docker build -t mcp-graphql-bridge .claude mcp add --transport stdio \
--env GRAPHQL_API_URL=https://your-api.example.com/graphql \
--env GRAPHQL_INTROSPECTION_URL=https://your-api.example.com/graphql \
--env GRAPHQL_TOKEN=your-bearer-token \
graphql-bridge -- docker run -i --rm \
-e GRAPHQL_API_URL -e GRAPHQL_INTROSPECTION_URL -e GRAPHQL_TOKEN \
mcp-graphql-bridgeNota: La bandera
-i(sin-t) es necesaria; mantiene stdin abierto para el protocolo stdio de MCP.
npm run dev # watch mode: rebuilds and restarts on file changes
npm run build # one-off TypeScript compile
npm start # run the compiled serverSi ves un error como:
Error: Cannot find module '/path/to/mcp-graphql-bridge/index.js'Estás apuntando al archivo incorrecto. El código fuente en TypeScript debe compilarse primero, y el punto de entrada se encuentra en la carpeta dist/:
Ruta correcta: /path/to/mcp-graphql-bridge/dist/index.js
Ruta incorrecta: /path/to/mcp-graphql-bridge/index.js
Solución:
Asegúrate de haber ejecutado npm run build (crea la carpeta dist/)
Actualiza tu configuración de MCP para usar la ruta completa que termina en /dist/index.js
Si el servidor se inicia pero muestra "Schema introspection failed", es posible que tu API GraphQL tenga la introspección deshabilitada en producción. Usa el comando curl en el paso 3 de la Configuración para pre-generar un archivo schema-introspection.json.
Ejecuta claude mcp list para verificar que el servidor esté registrado
Ejecuta /mcp en una sesión de Claude Code para ver las herramientas disponibles
Comprueba que todas las variables de entorno requeridas estén configuradas (GRAPHQL_API_URL, GRAPHQL_INTROSPECTION_URL, GRAPHQL_TOKEN)
Execute any GraphQL query or mutation against the API. Use this when no specific tool exists for your operation.
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | Full GraphQL query or mutation string including selection set | |
| variables | No | Variables for the operation | |
| bearer_token | No | Bearer token to authenticate this request (overrides GRAPHQL_TOKEN) | |
| custom_headers | No | Additional request headers as key-value pairs, e.g. {"X-Tenant-ID": "abc"} |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so description must disclose behavioral traits. It does not mention potential side effects of mutations, authentication requirements (beyond parameter hints), rate limits, or error handling. The description is too minimal to convey safe usage.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences pack purpose and usage guidelines with zero waste, frontloading the key action and fallback use.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
No output schema; description does not explain return format, errors, or the fact that the endpoint is pre-configured. Despite the complexity of a generic GraphQL executor, the description is incomplete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% (all 4 parameters have descriptions). The description adds no additional parameter semantics. Baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states 'Execute any GraphQL query or mutation against the API', specifying the verb and resource. It distinguishes itself from sibling 'get_type_details' by being a generic executor.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly says 'Use this when no specific tool exists for your operation', providing clear when-to-use guidance. No exclusions, but the instruction is direct.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Get fields of a specific GraphQL type to know what to put in __fields
| Name | Required | Description | Default |
|---|---|---|---|
| typeName | Yes | GraphQL type name, e.g. 'Repository', 'User', 'Issue' |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must disclose all behavioral traits. It indicates a read operation, but does not mention error handling (e.g., invalid type name), response structure, or any side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, focused sentence with no extraneous text. It is front-loaded and efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Despite the tool's simplicity, the description omits output details. The agent does not know whether the response returns field names, types, or full schema; this is critical given no output schema.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already covers the single parameter with a clear description and examples. The tool description adds no extra meaning beyond prompting usage of '__fields'.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool gets fields of a specific GraphQL type and its purpose in GraphQL introspection. However, it does not differentiate from sibling tool execute_graphql, which may also retrieve type information.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The phrase 'to know what to put in __fields' implies a use case, but there is no explicit guidance on when to use this tool versus execute_graphql, nor any when-not-to-use advice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
v2.1.0execute_graphql2 fields changedInput schema / properties / bearer_tokenAdded value: +{
+ "description": "Bearer token to authenticate this request (overrides GRAPHQL_TOKEN)",
+ "type": "string"
+}Input schema / properties / custom_headersAdded value: +{
+ "additionalProperties": {
+ "type": "string"
+ },
+ "description": "Additional request headers as key-value pairs, e.g. {\"X-Tenant-ID\": \"abc\"}",
+ "type": "object"
+}get_type_details1 field changedInput schema / properties / typeName / descriptionPrevious value: -"GraphQL type name, e.g. 'Machine', 'WorkOrder', 'Shift'"New value: +"GraphQL type name, e.g. 'Repository', 'User', 'Issue'"v1.0.1execute_graphqlget_type_detailsScored across 2 tools
The two tools serve clearly distinct purposes: executing GraphQL operations vs. retrieving type metadata. No overlap in functionality.
Both tool names follow a consistent verb_noun pattern using snake_case (execute_graphql, get_type_details), making the intent clear and predictable.
For a GraphQL bridge, two tools is minimal but still covers the essential operations of executing queries and exploring types. Slightly under-scoped but reasonable.
The tool surface covers core GraphQL operations (any query/mutation) and type introspection. Minor gaps exist (e.g., no dedicated tool for listing mutations), but the generic execute tool and type details suffice for agents familiar with GraphQL.
The Grafbase MCP server sits in front of a GraphQL API and exposes an MCP protocol-compliant interface that allows AI agents and LLMs to explore and query GraphQL APIs using natural language. It provides tools to search schemas, introspect types and fields, and execute GraphQL queries while minimizing context bloat by returning only relevant schema subsets, with built-in support for authentication, authorization, and configurable access control.
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