Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add Redtropig/harness-anchor/plugin install harness-anchorWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/redtropig/harness-anchor/anti-hallucination-gates)<a href="https://agentmods.dev/skills/redtropig/harness-anchor/anti-hallucination-gates"><img src="https://agentmods.dev/badge/skills/redtropig/harness-anchor/anti-hallucination-gates/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/redtropig/harness-anchor/anti-hallucination-gates"><img src="https://agentmods.dev/badge/skills/redtropig/harness-anchor/anti-hallucination-gates.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00072 | $0.02530 |
| Opus 5 | $0.00036 | $0.01265 |
| Sonnet 5 | $0.00014 | $0.00506 |
| Haiku 4.5 | $0.00007 | $0.00253 |
Grade A, and why
anti-hallucination-gates scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Anti-Hallucination Gates
The most common agent failure is declaring victory too early. This skill is the gate between "I think it works" and "evidence proves it works".
The Iron Rule
No claim of "done" / "fixed" / "passing" without a concrete artifact path proving it.
A claim like "I fixed the bug" is incomplete. The proper form:
"Fixed by commit
abc123. Testtests/foo.test.ts::handles-edge-casenow passes (output captured in.harness-anchor/test-2026-05-28.log). Build still passes (.build/last-build.logexit 0)."
The Iron Rule runs both ways
The rule above governs claims that something IS. Claims that something IS NOT are the same failure with the sign flipped, and until v0.17.0 this skill said nothing about them.
No claim that something is absent without stating the scope you actually searched and when you looked.
"clang-tidy isn't installed on this machine" is incomplete in exactly the way "I fixed the bug" is incomplete. The proper form:
"searched PATH + the VS-bundled LLVM and CMake directories, not found (as of 2026-07-29)"
Two classes, two probes
| Class | Sounds like | What counts as evidence |
|---|---|---|
| Capability | "not installed", "not available here", "this platform can't do X" | The search chain's coverage plus the date you looked. C/C++ tools: bash ${CLAUDE_PLUGIN_ROOT}/scripts/cpp-tool-discovery.sh <tool> — its NOT_FOUND line already enumerates its own scope. Other ecosystems: command -v plus that platform's known install locations. |
| Search | "there's no such function", "nothing tests this", "that option isn't in the config" | The command you actually ran and its coverage: which paths, which glob, case-sensitive or not, whether ignored files were included. |
An empty result proves only that your search found nothing. That is a different proposition from the thing is absent, and conflating the two is what this section exists to stop.
The "there is no" detector
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 188 lines · 0 tokens per session scan A 68cda5de3133
anti-hallucination-gates is a skill published in the GitHub repository Redtropig/harness-anchor (13 stars, last pushed 1mo ago), licensed MIT. It adds 72 tokens to every session and 2,530 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
testing-e2e
End-to-end testing patterns with Playwright — page objects, AI agent testing, visual regression, accessibility testing with axe-core, and CI integration. Use when writing E2E tests, setting up Playwright, implementing visual regression, or testing accessibility.
testing-llm
LLM and AI testing patterns — mock responses, evaluation with DeepEval/RAGAS, structured output validation, and agentic test patterns (generator, healer, planner). Use when testing AI features, validating LLM outputs, or building evaluation pipelines.
bare-eval
Run isolated eval and grading calls using CC 2.1.81 --bare mode. Constructs claude -p --bare invocations for skill evaluation, trigger testing, and LLM grading without plugin/hook interference. Use when running eval pipelines, grading skill outputs, benchmarking prompt quality, or testing trigger accuracy in isolation.
golden-dataset
Golden dataset lifecycle patterns for curation, versioning, quality validation, and CI integration. Use when building evaluation datasets, managing dataset versions, validating quality scores, or integrating golden tests into pipelines.
paired-probe
Refuse a verdict a probe did not earn. Runs a check where the fault IS present and where it is NOT, and blocks the answer when both arms print the same thing, because a check that cannot disagree with you has measured nothing. Also catches the zero-sample sweep that reads as "clean" and the swallowed error that reads…
testing-patterns
Redirect — testing-patterns was split into 5 focused sub-skills. Use when looking for testing-patterns, writing tests, or test automation. Redirects to testing-unit, testing-e2e, testing-integration, testing-llm, or testing-perf.