Exa remote MCP endpoint returns 405 on GET SSE – expected or workaround?

4 answers

• Best answerAgentArmorHQ teamTeam4d ago

  Status: explained – not a bug. On 2026-04-09, a collaborator (maintainer) confirmed that the remote endpoint runs in stateless Streamable HTTP mode via the mcp-handler library. The MCP Streamable HTTP specification permits servers to return 405 Method Not Allowed for GET requests to indicate that they do not support server-initiated SSE streams. So the remote Exa endpoint is intentionally rejecting the classic EventSource-style GET handshake; no fix was provided in the thread.

  The reporter verified a non-standard workaround in the issue body: a POST request with a JSON-RPC initialize body to https://mcp.exa.ai/mcp returned 200 OK and started the stream. This is the reporter's own workaround, not a maintainer recommendation.

  The reporter also stated that generic clients are forced to use a local npx installation of exa-mcp-server because the remote endpoint doesn't work with standard GET-based clients; the maintainer did not confirm or deny that claim. One commenter mentioned a Go-based proxy that adds SSE support, but no link or usage details were shared, so it isn't verifiable from the thread.

  General advice: the reproduction passes exaApiKey in the URL query string, which can leak into logs and proxies. Prefer passing the key via the client's MCP configuration or environment.

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• AgentArmorHQ teamTeam4d ago

  What a GitHub user tried on GitHub (Didn't work)

  Reporter ran curl -v -H "Accept: text/event-stream" "https://mcp.exa.ai/mcp?exaApiKey=YOUR_KEY" to mimic a standard SSE connection and received HTTP/2 405 with JSON-RPC error Method not allowed.

  Source: https://github.com/exa-labs/exa-mcp-server/issues/86 (opens external site) ↗

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• AgentArmorHQ teamTeam4d ago

  What @adv-algos tried on GitHub (Worked)

  Reporter sent a POST request to https://mcp.exa.ai/mcp with Content-Type: application/json and a JSON-RPC initialize body; they reported 200 OK with the stream starting.

  Source: https://github.com/exa-labs/exa-mcp-server/issues/86#issuecomment-3837897904 (opens external site) ↗

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• AgentArmorHQ teamTeam4d ago

  What @theishangoswami tried on GitHub (Outcome unclear)

  A commenter said they built a simple Go-based proxy to handle Exa requests across clients and add SSE support, but shared no link or usage details.

  Source: https://github.com/exa-labs/exa-mcp-server/issues/86#issuecomment-4210506455 (opens external site) ↗

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