feat: add mcp plugin implementation

[adambenhassen]

No description provided.

[gemini-code-assist]

Summary of Changes

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This pull request introduces the Model Context Protocol (MCP) integration into the GraphQL Hive Gateway. It enables the gateway to expose its underlying GraphQL operations as discoverable and executable "tools" for AI agents or other MCP-compatible clients. This is achieved through a new useMCP plugin, which handles MCP request routing, tool registration based on GraphQL schema introspection, and execution of GraphQL operations as defined by the protocol.

Highlights

• Model Context Protocol (MCP) Integration: Introduced a new useMCP plugin within the gateway runtime, enabling the exposure of GraphQL operations as discoverable and executable tools for AI agents or other MCP-compatible clients.
• Gateway Configuration for MCP: Added MCPConfig to the gateway's CLI configuration, allowing users to easily enable and configure the MCP endpoint and define which GraphQL operations should be exposed as tools.
• Core MCP Logic Implementation: Developed a dedicated mcp module within the @graphql-hive/gateway-runtime package, encompassing the ToolRegistry, createMCPHandler, createGraphQLExecutor, and schema-converter utilities to manage tool registration, protocol handling, execution, and JSON schema generation from GraphQL types.
• Example Usage: Included a new example (examples/mcp-example/run.ts) demonstrating how to set up a GraphQL subgraph and a gateway with the useMCP plugin, exposing mock weather API queries as MCP tools.

Changelog

• examples/mcp-example/run.ts
  • Added a new example demonstrating a GraphQL subgraph and a gateway configured with the new useMCP plugin.
  • The example defines a mock weather API with weather and forecast queries.
  • It configures the useMCP plugin to expose these queries as get_weather and get_forecast tools.
• packages/gateway/src/cli.ts
  • Imported MCPConfig type.
  • Added an optional mcp property to GatewayCLIBuiltinPluginConfig to allow MCP configuration via the CLI.
• packages/gateway/src/config.ts
  • Implemented dynamic loading and activation of the useMCP plugin based on the gateway configuration.
• packages/runtime/package.json
  • Added @modelcontextprotocol/sdk as a new dependency.
• packages/runtime/src/index.ts
  • Exported useMCP, MCPConfig, and MCPToolConfig to make the MCP plugin publicly accessible.
• packages/runtime/src/mcp/executor.ts
  • Added createGraphQLExecutor to handle the execution of GraphQL operations for MCP tools, including passing request headers.
• packages/runtime/src/mcp/index.ts
  • Created an index file to consolidate exports for the new MCP module.
• packages/runtime/src/mcp/protocol.ts
  • Added createMCPHandler to implement the server-side logic for the Model Context Protocol, handling initialize, tools/list, and tools/call methods.
• packages/runtime/src/mcp/registry.ts
  • Introduced ToolRegistry to manage and register GraphQL operations as MCP tools, including generating JSON schemas for their inputs.
• packages/runtime/src/mcp/schema-converter.ts
  • Added utility functions graphqlTypeToJsonSchema and operationToInputSchema to convert GraphQL types and operation variables into JSON Schema format.
• packages/runtime/src/plugins/useMCP.ts
  • Implemented the useMCP gateway plugin, which sets up the MCP endpoint, manages schema introspection, and integrates the MCP handler and executor.
• yarn.lock
  • Updated with new dependencies, including @modelcontextprotocol/sdk and its transitive dependencies.

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[theguild-bot]

🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@graphql-hive/gateway	2.5.10-alpha-fe6fd314380b611e2f6571d873a9595463235dc8	npm ↗︎ unpkg ↗︎
@graphql-hive/nestjs	2.0.51-alpha-fe6fd314380b611e2f6571d873a9595463235dc8	npm ↗︎ unpkg ↗︎
@graphql-hive/plugin-mcp	0.1.0-alpha-fe6fd314380b611e2f6571d873a9595463235dc8	npm ↗︎ unpkg ↗︎

[gemini-code-assist]

Code Review

This pull request introduces a prototype implementation of the Model Context Protocol (MCP) as a gateway plugin. The changes are extensive, adding the useMCP plugin, supporting logic for protocol handling, schema conversion to JSON Schema, and an example implementation. The overall structure is sound, but there are a few critical issues related to handling asynchronous operations and validating inputs that could lead to runtime errors and unreliable behavior. I've provided specific comments and suggestions to improve the robustness and correctness of the implementation.

[theguild-bot]

🚀 Snapshot Release (Binary for Linux-ARM64)

The latest changes of this PR are available for download (based on the declared changesets).

[theguild-bot]

🚀 Snapshot Release (Binary for Linux-X64)

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[theguild-bot]

🚀 Snapshot Release (Binary for macOS-ARM64)

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[theguild-bot]

🚀 Snapshot Release (Bun Docker Image)

The latest changes of this PR are available as image on GitHub Container Registry (based on the declared changesets):

ghcr.io/graphql-hive/gateway:2.5.10-alpha-fe6fd314380b611e2f6571d873a9595463235dc8-bun

[theguild-bot]

🚀 Snapshot Release (Node Docker Image)

The latest changes of this PR are available as image on GitHub Container Registry (based on the declared changesets):

ghcr.io/graphql-hive/gateway:2.5.10-alpha-fe6fd314380b611e2f6571d873a9595463235dc8

[theguild-bot]

🚀 Snapshot Release (Binary for macOS-X64)

The latest changes of this PR are available for download (based on the declared changesets).

[theguild-bot]

🚀 Snapshot Release (Binary for Windows-X64)

The latest changes of this PR are available for download (based on the declared changesets).