anyapi-mcp-server

If it has an API, you can MCP it.

Traditional MCP servers hand-pick a handful of endpoints and call it a day — locking you into whatever subset someone decided was "enough." Why settle for a fraction of an API when you can have all of it?

anyapi-mcp-server is a universal MCP server that connects any REST API to AI assistants like Claude, Cursor, and other LLM-powered tools — just point it at an OpenAPI spec or Postman collection. Every endpoint the API provides becomes available instantly, with GraphQL-style field selection and automatic schema inference. No custom server code, no artificial limits.

Quick start

1. Install

npm install -g anyapi-mcp-server

2. Add to your MCP client (Cursor, Claude Desktop, etc.)

{
  "mcpServers": {
    "your-api": {
      "command": "npx",
      "args": [
        "-y",
        "anyapi-mcp-server",
        "--name", "your-api",
        "--spec", "path/to/openapi.json",
        "--base-url", "https://api.example.com",
        "--header", "Authorization: Bearer ${API_KEY}"
      ],
      "env": {
        "API_KEY": "your-api-key"
      }
    }
  }
}

3. Use the tools — discover endpoints with list_api, inspect schemas with call_api, fetch data with query_api.

Provider examples

Ready-to-use configurations for popular APIs:

These work with any API that has an OpenAPI or Postman spec — the above are just examples. Stripe, Twilio, Shopify, HubSpot, and anything else with a REST API will work the same way.

CLI reference

Required flags

Optional flags

OAuth flags

For APIs that use OAuth 2.0 instead of static tokens. If any of the three required flags is provided, all three are required. All flags support ${ENV_VAR}.

See the Google Workspace guide for a complete OAuth example.

Tools

The server exposes four tools (plus auth when OAuth is configured):

list_api — Browse endpoints

Discover what the API offers. Call with no arguments to see all categories, provide category to list endpoints in a tag, or search to find endpoints by keyword.

call_api — Inspect an endpoint

Makes a real HTTP request and returns the inferred GraphQL schema (SDL) — not the data itself. Use this to discover the response shape and get suggestedQueries you can copy into query_api. Also returns per-field token costs (fieldTokenCosts) and a dataKey for cache reuse. For PUT/PATCH requests, automatically creates a pre-write backup (returns backupDataKey). Supports bodyFile for large payloads and blocks requests with detected placeholder values.

query_api — Fetch data

Fetches data and returns only the fields you select via a GraphQL query. Supports both reads and writes (mutations for POST/PUT/DELETE/PATCH). Pass a dataKey from call_api to reuse cached data with zero HTTP calls.

# Read
{ items { id name status } _count }

# Write
mutation { post_endpoint(input: { name: "example" }) { id } }

Key parameters:

• maxTokens — token budget for the response. Arrays are truncated to fit. Without this or unlimited, responses over ~10k tokens are rejected.
• unlimited — set to true to return the full response with no token budget enforcement.
• dataKey — reuse cached data from a previous call_api or query_api response.
• jsonFilter — dot-path to extract nested values after the GraphQL query (e.g. "data[].attributes.name").
• bodyFile — absolute path to a JSON file to use as request body (mutually exclusive with body). Use for large payloads that can't be sent inline.
• skipBackup — skip the automatic pre-write backup for PUT/PATCH requests (default: false).

explain_api — Read the docs

Returns spec documentation for an endpoint (parameters, request body schema, response codes) without making an HTTP request.

auth — OAuth authentication

Only available when --oauth-* flags are configured. Manages the OAuth flow:

• action: "start" — returns an authorization URL (or exchanges credentials for client_credentials)
• action: "exchange" — completes the authorization code flow (callback is captured automatically)
• action: "status" — shows current token status

Tokens are persisted and refreshed automatically.

Typical workflow

list_api          → discover what's available
     ↓
explain_api       → read the docs for an endpoint
     ↓
call_api          → inspect the response schema (returns dataKey)
     ↓
query_api         → fetch exactly the fields you need (pass dataKey for zero HTTP calls)
     ↓
query_api         → re-query with different fields using the same dataKey

How it works

OpenAPI/Postman spec
        │
        ▼
   ┌─────────┐  ┌─────────────┐  ┌──────────┐  ┌───────────┐
   │list_api │  │ explain_api │  │ call_api │  │ query_api │
   │(browse) │  │   (docs)    │  │ (schema) │  │  (data)   │
   └─────────┘  └─────────────┘  └──────────┘  └───────────┘
        │          │ no HTTP          │               │
        ▼          ▼ request          ▼               ▼
   Spec index   Spec index     REST API call    dataKey cache
   (tags,       (params,       (with retry)     hit → no HTTP
    paths)       responses,         │            miss → fetch
                 body schema)       ▼               │
                               Infer schema +       ▼
                               return dataKey   Execute GraphQL
                                                + token budget
                                                  truncation

Features

• Any REST API — provide an OpenAPI (JSON/YAML) or Postman Collection v2.x spec as a file or URL
• Remote spec caching — HTTPS specs are fetched once and cached to ~/.cache/anyapi-mcp/
• GraphQL field selection — query only the fields you need from any response
• Schema inference — automatically builds GraphQL schemas from live API responses
• Multi-sample merging — samples up to 10 array elements for richer schemas
• Mutation support — write operations get typed GraphQL mutations from OpenAPI body schemas
• Smart suggestions — call_api returns ready-to-use queries based on the inferred schema
• Response caching — filesystem-based cache with 5-min TTL; dataKey tokens let query_api reuse data with zero HTTP calls
• Token budget — query_api enforces a ~10k token safety limit by default; use maxTokens to truncate the deepest largest array to fit, or unlimited: true for full responses
• Per-field token costs — call_api returns a fieldTokenCosts tree so the LLM can make informed field selections
• Rate limit tracking — parses X-RateLimit-* headers and warns when limits are nearly exhausted
• Pagination detection — auto-detects cursor, next-page-token, and link-based pagination patterns in responses
• JSON filter — query_api accepts a jsonFilter dot-path for post-query extraction (e.g. "data[].name")
• Retry with backoff — automatic retries for 429/5xx with exponential backoff and Retry-After support
• Multi-format — parses JSON, XML, CSV, and plain text responses
• Safe writes — PUT/PATCH requests automatically snapshot the resource before writing (backupDataKey); placeholder values (e.g. PLACEHOLDER, TODO, file://) are detected and blocked before sending
• File-based body — bodyFile parameter accepts an absolute path to a JSON file, enabling large payloads that can't be sent inline
• Rich errors — structured error messages with status-specific suggestions and spec context for self-correction
• OAuth 2.0 — Authorization Code (with PKCE) and Client Credentials flows with automatic token refresh
• Env var interpolation — ${ENV_VAR} in base URLs, headers, and spec paths
• Request logging — optional NDJSON log with sensitive header masking

Supported spec formats

• OpenAPI 3.x (JSON or YAML)
• OpenAPI 2.0 / Swagger (JSON or YAML)
• Postman Collection v2.x (JSON)

License

Proprietary Non-Commercial. Free for personal and educational use. Commercial use requires written permission. See LICENSE for details.