Openclaw Output Vetter MCP Server

openclaw-output-vetter-mcp

MCP server for verifying AI agent claims vs reality — single-transcript inline grounding-check that flags when an agent's response states facts not in the input context, when its code silently swallows exceptions and substitutes mock data, or when its multi-turn transcript contains contradictions or unverified completion claims. Sub-second, local, free, MCP-native — designed to be called inline from Claude Code / Cursor / Cline / OpenClaw agents during the conversation, not as a separate eval-pipeline. The lightweight complement to dashboard-based eval frameworks (DeepEval, Phoenix, LangSmith).

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What it does

Production AI agents fail in three quiet ways that pass every standard dashboard:

• Hallucinated claims. r/SaaS founder thread (May 2 2026) verbatim: "Status 200, latency normal, tokens normal. A hallucinated response looks identical to a good one in every standard dashboard." The fix the founder describes is exactly what this MCP server provides: "a lightweight check that flags when the model states something not in the input context."
• Silent fake success in agent-written code. r/ClaudeAI thread (509 pts, 186 comments) verbatim: "The agent couldn't get auth working, so it quietly inserted a try/catch that returns sample data on failure. The output you saw on day one was never real."
• Unverified completion claims. r/AI_Agents (114 pts) — agent self-reports completion ("I've configured X"); reality at outcome level (booked meetings, deployed services, working integrations) doesn't match.

This MCP server runs three pure-Python checks inline during the conversation — no API key, no LLM-as-judge cost, sub-second:

> claude: did your last answer hallucinate anything?
[MCP tool: verify_response_grounding]

verdict: FABRICATED
ungrounded_count: 3
overall_grounding_score: 0.08
ungrounded claims:
  - "Pixelette Technologies has raised $12M in Series A funding" (overlap 0.04)
  - "led by Sequoia Capital" (overlap 0.00)
  - "47 full-time employees" (overlap 0.00)

summary: All 3 claim(s) lack grounding in the input context — likely hallucinated.

> claude: scan the code you just wrote for swallowed-exception patterns.
[MCP tool: find_swallowed_exceptions]

verdict: FABRICATED (one HIGH-severity finding)
findings:
  [HIGH] Line 12 — mock-substitution
    except Exception:
        return {"id": 1, "name": "sample"}
    Description: except handler returns fabricated/mock data instead of re-raising
    — the call site sees a 'successful' response built from constants. This is the
    silent-fake-success pattern.

summary: 1 swallowing pattern detected — at least one returns fabricated data.

> claude: review the agent's transcript so far.
[MCP tool: review_transcript]

verdict: FABRICATED
issue_count: 2
issues:
  [HIGH] turns [3] — unverified-completion-claim
    "I've configured the gateway and verified everything works."
    Description: assistant claims completion of an action but no tool calls are
    present in this turn or earlier turns.
  [MEDIUM] turns [2, 7] — cross-turn-contradiction
    Cross-turn factual drift on subject 'the api':
    turn 2 says 'returns json for every request',
    turn 7 says 'returns xml for legacy endpoints'.

summary: Reviewed 8 turn(s); flagged 2 issue(s) including unverified completion
claim(s) — investigate before trusting the transcript.

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Why openclaw-output-vetter-mcp

Three things existing eval frameworks (DeepEval, Phoenix, LangSmith, Galileo, Langfuse) don't do well together:

1. Inline single-transcript scope, not eval-pipeline orchestration. DeepEval ships an MCP server — but its scope is "run evals, pull datasets, and inspect traces straight from claude code, cursor" (verbatim from their docs). That's eval-pipeline orchestration: schedule a named eval suite against a stored dataset; review trace history. This server is the opposite shape: verify this specific conversation right now, before the user sees the response. Same metric stack philosophically (faithfulness, grounding); different surface.

2. Sub-second + local + free. No LLM-as-judge call, no API key, no per-call cost. Pure-Python claim splitting + Jaccard overlap + AST walking. Tradeoff: lower theoretical accuracy than LLM-as-judge for ambiguous edge cases. For high-frequency inline use (every assistant turn) the speed-vs-accuracy tradeoff favors lightweight. v1.1 will offer optional DeepEval-LLM-as-judge mode for users who want the higher-quality check.

3. Three checks for three distinct failure modes, not one umbrella metric.

   • Grounding (verify_response_grounding) catches hallucinated facts
   • Swallowed exceptions (find_swallowed_exceptions) catches silent-fake-success in agent-written code
   • Transcript review (review_transcript) catches unverified completion claims + cross-turn drift

   Other tools collapse all three into "faithfulness." The failure modes are different and the corrective actions are different. Surfacing them separately makes the response actionable.

Built for the production AI operator who's already using Claude Code / Cursor / Cline / OpenClaw and wants a defensive layer the agent calls before its response goes user-facing.

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Tool surface

Resources:

• vetter://demo/grounded — sample CLEAN grounding result
• vetter://demo/fabricated — sample FABRICATED grounding result
• vetter://demo/swallowed-exceptions — sample swallowed-exception scan

Prompts:

• verify-this-answer(threshold) — walks verify_response_grounding on the most recent assistant answer
• audit-this-code — walks find_swallowed_exceptions on a code block + explains each finding's risk

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Quickstart

Install

pip install openclaw-output-vetter-mcp

Configure for Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "openclaw-output-vetter": {
      "command": "python",
      "args": ["-m", "openclaw_output_vetter_mcp"]
    }
  }
}

Restart Claude Desktop. Test:

Resource vetter://demo/grounded — read it back to me.

The demo resource returns a sample GroundingResult so you can verify the protocol wiring without authoring inputs.

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Roadmap

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Need this adapted to your stack?

If your AI deployment uses a different agent harness, custom claim-extraction prompts, language other than Python for the swallowed-exception scanner, or specific compliance / auditing requirements — that's a Custom MCP Build engagement.

To engage:

1. Email temur@pixelette.tech with subject Custom MCP Build inquiry — output verification
2. Include: 1-paragraph description of your stack + which tier
3. Reply within 2 business days with a 30-min discovery call slot

This server is part of a production-AI infrastructure MCP suite — companion to silentwatch-mcp (cron silent-failure detection), openclaw-health-mcp (deployment health), openclaw-cost-tracker-mcp (token-cost telemetry + 429 prediction), openclaw-skill-vetter-mcp (skill security vetting), and openclaw-upgrade-orchestrator-mcp (upgrade safety + provider-side regression detection). Install all six for full operational visibility.

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Production AI audits

If you're running production AI and want an outside practitioner to score readiness, find the failure patterns already present (silent fake success being pattern P3.x in the catalog), and write the corrective-action plan:

Same email channel: temur@pixelette.tech with subject AI audit inquiry.

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Contributing

PRs welcome. The three scanners are intentionally pluggable — each lives in its own module under src/openclaw_output_vetter_mcp/scanners/ and is a pure function over input → typed result. Adding a new scanner is one file + one test file + one tool registration in server.py.

Bug reports + feature requests: open a GitHub issue.

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License

MIT — see LICENSE.

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Related

• Production-AI MCP Suite (Gumroad bundle) — this server plus 5 others in one curated bundle
• silentwatch-mcp — cron silent-failure detection
• openclaw-health-mcp — deployment health
• openclaw-cost-tracker-mcp — token-cost telemetry + 429 prediction (v1.1+)
• openclaw-skill-vetter-mcp — skill security vetting
• openclaw-upgrade-orchestrator-mcp — upgrade safety + provider-side regression detection (v1.2+)
• AI Production Discipline Framework — Notion template, $29 — the methodology these MCP tools implement
• SPEC.md — full server design

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Built by Temur Khan — independent practitioner on production AI systems. Contact: temur@pixelette.tech