OAuth on MCP is not the same as authorizing each tool call
OAuth on MCP answers “who is calling?” It does not, by itself, answer whether a particular tools/call should run. The 2026-07-28 MCP spec tightens auth and routing with issuer validation, the CIMD direction, and Mcp-Method / Mcp-Name headers. Those are useful signals, but authentication is still only one decision: AuthN verifies who is calling; tool-call authorization asks whether this principal…
We haven't written up this one. Dev.to has the full story — the link below goes straight to it.
