OpenAPI MCP

MCP server for loading and exploring OpenAPI/Swagger specifications. Lets AI assistants browse API contracts dynamically — load any OpenAPI spec, search endpoints, inspect schemas, retrieve operations, diff versions — all through MCP tools.

Usage

Prerequisites

• Node.js >= 22 or Bun >= 1.0
• oasdiff (optional) — required only for the diff_specs tool. Install from github.com/oasdiff/oasdiff.

Manually

Add to your MCP client config:

{
  "mcpServers": {
    "openapi-mcp": {
      "command": "npx",
      "args": ["-y", "@ceski23/openapi-mcp"]
    }
  }
}

Via AI agent

Ask your AI assistant to add it:

Add the MCP server @ceski23/openapi-mcp to my config. Run it with npx -y @ceski23/openapi-mcp via stdio.

Most assistants can modify your MCP config file directly.

Tools

| Tool | Description | |---|---| | load_spec | Load an OpenAPI/Swagger spec from a URL or local file path. Parses and validates the spec, returns a specId for use by other tools. | | find_operations | Search operations in a loaded spec by operationId, path, summary, tags, or description. Supports filtering by HTTP method and tags, with pagination. | | get_operation | Get full details for a single operation by operationId — method, path, parameters, requestBody, and responses. | | get_path | Get all HTTP methods defined on a specific path. Returns a summary of each method. | | find_schemas | Search component/definition schema names in a loaded spec. Supports pagination. | | get_schema | Retrieve a fully dereferenced component/definition schema by name. | | search_contract | Search both operations and schemas in a single call — matches against operationIds, summaries, tags, paths, schema names, schema descriptions, property names, and enum values. The best first call when exploring an API. | | diff_specs | Compare two loaded OpenAPI specs. Supports summary, detailed (JSON), and markdown changelog output. Requires oasdiff on PATH. | | list_cached_specs | List all currently cached specs with their specIds, sources, titles, and versions. | | list_versions | List all cached versions for a specId (tracked across repeated loads of the same source). | | unload_spec | Remove a loaded spec (and its version history) from the cache by specId. |