princekrroshan01/mcp-auth-server repository overview

⁠mcp-auth

A provider-neutral OAuth 2.1 authorization broker for the Model Context Protocol (MCP) ecosystem. mcp-auth sits between MCP clients and resource servers on one side and an organization's upstream identity provider on the other. It provides a standalone authorization server, plus Python, Go, and TypeScript SDKs for the resource-server side.

It separates three concerns that are often coupled:

• MCP clients complete the OAuth 2.1 Authorization Code flow with mandatory PKCE S256.
• MCP resource servers validate narrowly scoped access tokens with reusable Python, Go, or TypeScript SDKs.
• Identity providers and downstream APIs stay behind runtime-configured connectors.

Both an OIDC provider (a connector requesting openid, with a verified ID token) and a plain OAuth 2.0 provider (no openid, identity from userinfo_endpoint) are supported. Endpoints may be configured directly or discovered from the issuer, and ID tokens may use RS256, PS256, or ES256. See connect an organization's identity provider⁠ for setup. The provider's upstream protocol is separate from the OAuth 2.1 flow between the MCP client and mcp-auth.

⁠Standards position

mcp-auth supports the MCP OAuth 2.1 authorization profile, including RFC 8414 Authorization Server Metadata, RFC 9728 Protected Resource Metadata, mandatory PKCE S256, resource indicators and audience-bound tokens, refresh-token rotation, RFC 9207 authorization-response iss, and Client ID Metadata Documents (CIMD), enabled by default. Set MCP_AUTH_CLIENT_ID_METADATA_ENABLED=false to opt out. MCP clients should prefer pre-registered credentials when available, then CIMD when the authorization server advertises support, and use Dynamic Client Registration (DCR) as a backwards-compatibility fallback. DCR is not a second registration step after CIMD. The authorization server brokers authorization; it is not an identity provider. MFA, directory policy, user lifecycle, and upstream credentials belong to the upstream IdP.

mcp-auth does not claim to implement every OAuth extension or every responsibility in the MCP specification. MCP clients, resource servers, and authorization servers have distinct normative responsibilities; the bundled authorization server and resource-server SDKs cover their respective roles.

⁠How it fits together

Editable Mermaid source⁠

The token sent by the MCP client is valid only for the MCP resource server. It is never forwarded to the downstream API; the resource server obtains a separate downstream credential through token exchange or the connector's upstream session.

⁠Try it

docker run --rm -p 8080:8080 \
  -e MCP_AUTH_ISSUER=http://localhost:8080 \
  -e MCP_AUTH_RESOURCES=http://localhost:8081/mcp \
  -e MCP_AUTH_LOCAL_DEVELOPMENT=true \
  -e MCP_AUTH_REQUIRE_HTTPS=false \
  princekrroshan01/mcp-auth-server:0.4.1

Local-development only — no TLS, no identity provider. See Authorization server⁠ before deploying it anywhere real.

⁠Choose your starting point

⁠Repository layout

• auth-server/ — standalone Go OAuth authorization server (github.com/Agent-Hellboy/mcp-auth/auth-server, tagged auth-server/vX.Y.Z)
• auth-client/go/ — Go resource-server SDK (github.com/Agent-Hellboy/mcp-auth/auth-client/go/mcpauth, tagged auth-client/go/vX.Y.Z)
• auth-client/python/ — Python resource-server SDK, including a FastMCP adapter
• auth-client/typescript/ — TypeScript resource-server SDK for Node.js
• examples/demo-mcp/ — dummy FastMCP resource server used by the Compose E2E
• examples/typescript-mcp/ — protected TypeScript MCP JSON-RPC server
• examples/go-mcp/ — protected Go MCP JSON-RPC server

The Python SDK installs from Git while its API settles:

python -m pip install "mcp-auth-client @ git+https://github.com/Agent-Hellboy/mcp-auth.git#subdirectory=auth-client/python"

MCP authorization is optional at the protocol level. A resource server may still require it when it exposes private data or actions.

⁠Contributors

• Prince Roshan

⁠License

MIT. See LICENSE⁠.