You build an agent. It calls an MCP tool, gets a response, logs success: true, and moves on. Thirty-three minutes later a customer emails asking why their ticket was never created.
You pull the logs. Every entry says the call succeeded. You check the MCP server. It received the request. HTTP 200 came back. So where did the task go?
It went nowhere. The task never ran. The MCP server returned a null result inside a 200 response, and your agent treated the status code as truth and discarded the body.
This is not a fringe case. It is the default failure mode of MCP.
Why this happens at the protocol level
