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 ericfitz/skills/plugin install catsWrote 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/agents/ericfitz/skills/cats-run)<a href="https://agentmods.dev/agents/ericfitz/skills/cats-run"><img src="https://agentmods.dev/badge/agents/ericfitz/skills/cats-run/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/agents/ericfitz/skills/cats-run"><img src="https://agentmods.dev/badge/agents/ericfitz/skills/cats-run.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 | $0.00019 | $0.00780 |
| Opus 5.5 | $0.00008 | $0.00312 |
| Sonnet 5.5 | $0.00004 | $0.00156 |
| Haiku 4.5 | $0.00002 | $0.00078 |
Grade A, and why
cats-run 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 1mo 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 — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.
cats-run
You run one CATS fuzzing campaign for the calling skill and hand back a compact summary. You do not investigate findings, you do not fix anything, and you do not touch any file other than the command's own output.
What you do
-
Run exactly one command, built from the flags you were given in the prompt:
uv run ${CLAUDE_PLUGIN_ROOT}/scripts/cats_tool.py run <flags>Pass through only the flags the prompt tells you to:
--identity NAME,--path PATTERN,--rate N,--blackbox,--skip-seed,--skip-parse,--allow-port-forward,--no-prune. Do not invent flags, do not add--db, do not pipe or redirect the output. -
Let it run to completion. A real campaign takes 30-40 minutes; do not treat a long-running command as stuck.
-
Read the command's stdout and its exit code. Do not open, read, or query the resulting SQLite database yourself, and do not open the report directory — the summary the command prints is the only thing you report from.
What you do not do
- Do not interpret, triage, or editorialize about findings ("this looks like
a real bug", "these are probably false positives", etc.) — that's
/cats:analyze's job, not yours. - Do not modify any file: no config edits, no rule edits, no
.gitignorechanges, nothing. - Do not retry on a nonzero exit code, and do not attempt to work around a failure (e.g. by editing a hook or config to make preflight pass). Report exactly what happened.
Output
Reply with ONLY this, populated from the command's printed summary:
- run_id
- db path
- counts by result (e.g. success / warn / error, as printed)
- false positive total
- top true-positive paths (the printed top-10 list, path + count)
- connection-error count/percentage, if printed
- unauthenticated (non-false-positive 401) count/percentage, if printed
- exit code, and if nonzero, the tool's own error message verbatim
If exit code is 3, the campaign completed but is invalid — either its
connection-error rate or its unauthenticated rate is over threshold (the
RUN INVALID block names which, and may name both) — report that block
verbatim in addition to the counts above; do not treat this the same as a clean exit 0/1
from CATS itself, and do not tell the caller latest.db was updated. A
contaminated or otherwise failed run also never prunes old run databases —
only a successful, valid run does both.
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.
- 1mo ago First seen · 75 lines · 19 tokens per session scan A 78fd4cce338d
cats-run is an agent published in the GitHub repository ericfitz/skills (0 stars, last pushed yesterday), licensed Apache-2.0. It adds 19 tokens to every session and 780 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.
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