MCP spec conformance: 4 requirement(s) violated (via @hasmcp/mcp-spec-test) — spec 2025-11-25

[hasmcp-dev]

Running the black-box @hasmcp/mcp-spec-test conformance suite against opfor's MCP server (built from source: npm install && npm run build --workspaces --if-present, then node runners/mcp/dist/index.js) against the older 2025-11-25 revision it also advertises support for shows the same root cause as the newer revision (see the companion report filed alongside this one), with a smaller downstream failure count: the server prints a plaintext startup banner to stdout — ◇ injected env (0) from .env // tip: ⌘ enable debugging { debug: true } — before any JSON-RPC traffic, corrupting the stdio framing the MCP client relies on, so the process is torn down before the handshake completes and 13 further checks can't be verified. This is a real framing bug, not a test-environment artifact: on stdio transport, an MCP server must write only JSON-RPC to stdout.

Conformance report

MCP 2025-11-25 conformance report

Verdict: not conformant — 4 requirements violated.

Target	sh -c '[ -d agent-opfor ] || git clone https://github.com/KeyValueSoftwareSystems/agent-opfor && cd agent-opfor && npm install && npm run build --workspaces --if-present && node runners/mcp/dist/index.js'
Transport	stdio
Revision tested	2025-11-25
Revisions supported	2026-07-28, 2025-11-25
Passed	3
Failed	4
Not verified	13
Cases applied	20
Duration	19290ms
Generated	2026-08-24T14:18:49.031Z
Tool	@hasmcp/mcp-spec-test 0.1.1

Failed (4)

the server deviates from the spec here

Version negotiation

• a request with no version at all is served on the default
  a version-less request must be served, got 0: {"_raw":"server exited"}

  0 !== 200

• an unsupported version offered at the handshake is refused or downgraded, not echoed
  expected either an error or a protocolVersion, got {"_raw":"server exited"}

Official SDK interop

• a stock official-SDK client completes the handshake
  MCP error -32000: Connection closed
• the handshake settles on a revision inside the supported window
  initialize must return a protocolVersion, got undefined

Not verified (13)

skipped; a skip is not a pass

Capability methods

• tools/list returns schema-conformant tools
  cannot determine what the target supports — initialize returned no result (status 0)
• tools/call on an unknown tool is an error, not a crash
  cannot determine what the target supports — initialize returned no result (status 0)
• tools/call returns a schema-conformant CallToolResult
  cannot determine what the target supports — initialize returned no result (status 0)
• prompts/list returns schema-conformant prompts
  cannot determine what the target supports — initialize returned no result (status 0)
• prompts/get returns messages with a role and content
  cannot determine what the target supports — initialize returned no result (status 0)
• resources/list returns schema-conformant resources
  cannot determine what the target supports — initialize returned no result (status 0)
• resources/templates/list returns schema-conformant templates
  cannot determine what the target supports — initialize returned no result (status 0)
• resources/read returns contents for every sampled resource
  cannot determine what the target supports — initialize returned no result (status 0)
• resources/read on an unknown uri is an error
  cannot determine what the target supports — initialize returned no result (status 0)
• following nextCursor terminates and does not repeat a page
  cannot determine what the target supports — initialize returned no result (status 0)
• an invalid pagination cursor is rejected (SHOULD)
  cannot determine what the target supports — initialize returned no result (status 0)

Version negotiation

• initialize returns the schema-required fields
  no session — initialize returned no result (status 0)
• the handshake settles on the revision under test
  no session — initialize returned no result (status 0)

Passed (3)

checked and conformant

server/discover

• the suite is reading a schema that matches the features it selected

Official SDK interop

• the official SDK does not yet implement the newest revision
• a stock official-SDK client can list tools

How to reproduce

With Docker:

docker pull hasmcp/mcp-spec-test:latest
docker run --rm hasmcp/mcp-spec-test -c "sh -c '[ -d agent-opfor ] || git clone https://github.com/KeyValueSoftwareSystems/agent-opfor && cd agent-opfor && npm install && npm run build --workspaces --if-present && node runners/mcp/dist/index.js'" --spec-version 2025-11-25

(on Apple Silicon / arm64 hosts, add --platform linux/amd64; the published image currently only ships an amd64 manifest but runs fine under emulation)

Without Docker (npx):

npx @hasmcp/mcp-spec-test@latest -c "sh -c '[ -d agent-opfor ] || git clone https://github.com/KeyValueSoftwareSystems/agent-opfor && cd agent-opfor && npm install && npm run build --workspaces --if-present && node runners/mcp/dist/index.js'" --spec-version 2025-11-25

You can see the offending stdout line directly with:

node runners/mcp/dist/index.js
# stdout prints: ◇ injected env (0) from .env // tip: ⌘ enable debugging { debug: true }

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This report was generated by an automated MCP conformance sweep across public MCP server repos. If this turns out to be a false positive specific to the test container/environment, or not applicable, feel free to close it. (A companion report against the 2026-07-28 revision this server also supports, with a larger failure set, is filed separately.)