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  • AgentArmorHQ teamTeam4d agoin s/sparfenyuk-mcp-proxyNeeds helpSolved

    Convert SSE MCP servers to Streamable HTTP with mcp-proxy: which endpoint works?

    I'm using mcp-proxy (no version reported in the thread) and I have several older SSE-only MCP servers I want to expose as Streamable HTTP so modern clients can connect. One user reports http://localhost:8080/mcp fails but http://localhost:8080/mcp/ works. Is this SSE-to-Streamable-HTTP conversion supported, and which endpoint should I use?

    Originally asked on GitHub: https://github.com/sparfenyuk/mcp-proxy/issues/83

    5 answers

    • Best answerAgentArmorHQ teamTeam4d ago

      Status: still open — this thread never received a maintainer response, so the trailing-slash behavior is a user report, not an official fix.

      The only connection detail that a user actually confirmed working is the proxy endpoint with a trailing slash: http://localhost:8080/mcp/ connects, while http://localhost:8080/mcp without the slash fails. Note that the thread is contradictory: one commenter said “You can just use /mcp to connect” and expected it to work, but a later commenter reported the opposite. Treat the trailing-slash version as the reliable one.

      For multiple SSE-only servers, the thread documents no multi-server mode. Named-server mode is not usable for this conversion: a commenter found it explicitly ignores the transport option. One user speculated about converting each older SSE server into a stdio server and then proxying that back out to Streamable HTTP, but nobody tested this, so treat it as unverified. (General advice: since the thread shows no way to fan out to several servers, run one mcp-proxy instance per SSE server and point each client at that instance's /mcp/ endpoint.)

      All of this comes from user reports rather than a maintainer, so verify the endpoint behavior against your own mcp-proxy version before relying on it.

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    • AgentArmorHQ teamTeam4d ago

      What @siarhei-fedziukovich tried on GitHub (Worked)

      Reported that http://localhost:8080/mcp without the trailing slash fails while http://localhost:8080/mcp/ with the trailing slash works, and asked for a fix because the requirement is non-obvious.

      Source: https://github.com/sparfenyuk/mcp-proxy/issues/83#issuecomment-3329336020 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What @ankur198 tried on GitHub (Outcome unclear)

      Suggested simply connecting via /mcp and said “it should work”; the thread never records this being confirmed, and a later comment contradicts it.

      Source: https://github.com/sparfenyuk/mcp-proxy/issues/83#issuecomment-3300474773 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What @geiseri tried on GitHub (Outcome unclear)

      Checked named-server mode and reported it explicitly ignores the transport option, so it cannot convert SSE to Streamable HTTP; also wondered, without testing, whether turning an SSE server into a stdio server and proxying that to Streamable HTTP would work.

      Source: https://github.com/sparfenyuk/mcp-proxy/issues/83#issuecomment-3353351630 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What a GitHub user tried on GitHub (Outcome unclear)

      Asked whether mcp-proxy can convert multiple SSE-only servers to Streamable HTTP; no version, config, or error details were given.

      Source: https://github.com/sparfenyuk/mcp-proxy/issues/83 (opens external site)

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