///// Checks / Connectability
MCP PKCE S256 support
Whether your authorization server advertises PKCE with the S256 method.
- Check id
mcp-pkce-s256- Pillar
- Connectability
- Runs in
- The free CLI
- Scoring
- Always counted when there is an MCP server
- Status
- Pre-release, in calibration
Why it matters
MCP hosts require PKCE. A server that doesn't advertise S256 can be refused by the host.
How to pass
Support PKCE and list code_challenge_methods_supported: ["S256"] in your authorization-server metadata.
Run it
Find mcp-pkce-s256 in the report. Add --md for a fix prompt you can paste into Claude Code, Codex or Cursor.