mcp_method_not_allowed

The MCP endpoint takes POST. Answered with 405.

What it means

The MCP server speaks the stateless Streamable HTTP transport: there is no GET stream to open and no session to delete.

What to do

POST each JSON-RPC message on its own, with an MCP-Protocol-Version header.

The body

{
  "type": "https://tigby.eu/problems/mcp_method_not_allowed",
  "title": "The MCP endpoint takes POST",
  "status": 405,
  "detail": "…what was refused, naming this request's own values",
  "code": "mcp_method_not_allowed",
  "doc_url": "https://docs.tigby.eu/errors/mcp_method_not_allowed",
  "agent_hint": "…the next step, for software"
}

Branch on code. The detail names this request's own Handle, id or limit and is not part of the contract.