OAuth for MCP Servers

MCP authorization for HTTP builds on OAuth security patterns rather than inventing a new token system.

Core requirements to understand

• Authorization endpoints use HTTPS.
• Public clients use PKCE.
• Clients discover authorization metadata rather than hardcoding everything.
• Tokens are bound to intended resources/audiences.
• Servers validate issuer, audience, expiration, and scope as appropriate.

2026 hardening

The 2026 protocol work strengthens issuer validation and moves the ecosystem toward Client ID Metadata Documents while deprecating Dynamic Client Registration as the long-term default.

Do not build OAuth from memory

Use a mature identity provider and supported SDKs. OAuth has many edge cases around redirect URIs, code interception, token storage, and discovery.