We ran @hasmcp/mcp-spec-test, a black-box MCP protocol conformance suite, against uvx docker-mcp. The server process appears to crash/close its connection immediately during the protocol handshake, so even a stock official MCP SDK client can't complete initialize. We suspected this might just be because our container had no Docker socket to talk to, but re-running with /var/run/docker.sock mounted through produced the identical result, so a missing Docker socket doesn't appear to be the explanation. This reproduced consistently across both spec revisions the server negotiates (2026-07-28 and 2025-11-25), so one issue covers both re-runs below.
Conformance report
Revision 2026-07-28
Verdict: not conformant — 10 requirements violated.
|
|
| Target |
uvx docker-mcp |
| Transport |
stdio |
| Revision tested |
2026-07-28 |
| Revisions supported |
2026-07-28, 2025-11-25 |
| Passed |
4 |
| Failed |
10 |
| Not verified |
22 |
| Cases applied |
36 |
| Duration |
33427ms |
| Tool |
@hasmcp/mcp-spec-test 0.1.1 |
Failed (10) — all downstream of the server closing the connection during handshake:
- server/discover is answered without a session or handshake — no response within 10000ms
- server/discover advertises the versions the server can serve
- server/discover is a CacheableResult with usable cache hints
- server/discover reports server identity and capabilities
- server/discover is stable across calls within its own TTL
- server/discover advertises a revision this suite supports
- a request with no version at all is served on the default — no response within 10000ms
- a stock official-SDK client completes the handshake —
MCP error -32000: Connection closed
- the handshake settles on a revision inside the supported window
- a stock official-SDK client can list tools —
MCP error -32000: Connection closed
Revision 2025-11-25
Verdict: not conformant — 5 requirements violated.
|
|
| Target |
uvx docker-mcp |
| Transport |
stdio |
| Revision tested |
2025-11-25 |
| Passed |
2 |
| Failed |
5 |
| Not verified |
13 |
| Cases applied |
20 |
| Duration |
5877ms |
Failed (5) — same root cause, and here the server explicitly reports as exited:
- a request with no version at all is served on the default —
{"_raw":"server exited"}
- an unsupported version offered at the handshake is refused or downgraded, not echoed —
{"_raw":"server exited"}
- a stock official-SDK client completes the handshake —
MCP error -32000: Connection closed
- the handshake settles on a revision inside the supported window
- a stock official-SDK client can list tools —
MCP error -32000: Connection closed
How to reproduce
With Docker:
docker pull hasmcp/mcp-spec-test:latest
docker run --rm --platform linux/amd64 hasmcp/mcp-spec-test -c "uvx docker-mcp"
Without Docker (npx):
npx @hasmcp/mcp-spec-test@latest -c "uvx docker-mcp"
Add --spec-version 2025-11-25 (or 2026-07-28) to test one revision at a time.
This issue was filed by an automated MCP conformance sweep. It's entirely possible this is a false positive specific to our test container/environment (e.g. some other missing dependency at startup) rather than a real bug — please feel free to close it if it doesn't reproduce on your end or isn't applicable.
We ran @hasmcp/mcp-spec-test, a black-box MCP protocol conformance suite, against
uvx docker-mcp. The server process appears to crash/close its connection immediately during the protocol handshake, so even a stock official MCP SDK client can't completeinitialize. We suspected this might just be because our container had no Docker socket to talk to, but re-running with/var/run/docker.sockmounted through produced the identical result, so a missing Docker socket doesn't appear to be the explanation. This reproduced consistently across both spec revisions the server negotiates (2026-07-28 and 2025-11-25), so one issue covers both re-runs below.Conformance report
Revision 2026-07-28
Verdict: not conformant — 10 requirements violated.
uvx docker-mcpFailed (10) — all downstream of the server closing the connection during handshake:
MCP error -32000: Connection closedMCP error -32000: Connection closedRevision 2025-11-25
Verdict: not conformant — 5 requirements violated.
uvx docker-mcpFailed (5) — same root cause, and here the server explicitly reports as exited:
{"_raw":"server exited"}{"_raw":"server exited"}MCP error -32000: Connection closedMCP error -32000: Connection closedHow to reproduce
With Docker:
Without Docker (npx):
Add
--spec-version 2025-11-25(or2026-07-28) to test one revision at a time.This issue was filed by an automated MCP conformance sweep. It's entirely possible this is a false positive specific to our test container/environment (e.g. some other missing dependency at startup) rather than a real bug — please feel free to close it if it doesn't reproduce on your end or isn't applicable.