Borrowing it
Nothing to install: this file belongs to datathings/marketplace. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/datathings/marketplace/main/.claude/commands/update_greycat.mdgit clone --depth 1 https://github.com/datathings/marketplaceWrote 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/commands/datathings/marketplace/update_greycat)<a href="https://agentmods.dev/commands/datathings/marketplace/update_greycat"><img src="https://agentmods.dev/badge/commands/datathings/marketplace/update_greycat/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/commands/datathings/marketplace/update_greycat"><img src="https://agentmods.dev/badge/commands/datathings/marketplace/update_greycat.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 | $0.00016 | $0.01512 |
| Opus 5.5 | $0.00006 | $0.00605 |
| Sonnet 5.5 | $0.00003 | $0.00302 |
| Haiku 4.5 | $0.00002 | $0.00151 |
Grade C, and why
update_greycat scanned grade C with 1 finding 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 2mo 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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
rm -rf ./plugins/greycat/skills/greycat/reference How it starts
The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Upgrade GreyCat Skills
Single maintenance command that syncs both GreyCat skills from the upstream ../greycat
checkout. It:
- Pulls the latest upstream sources (
git pullin../greycat) - Upgrades the greycat skill — a straight copy of the upstream skill docs
- Upgrades the greycat-c skill — analyzes the upstream C headers and updates the docs
- Re-packages both
.skillfiles
All paths below are relative to the marketplace repo root (where this command is run).
../greycat resolves to the sibling GreyCat checkout (a git repo).
Step 0: Pull Latest Upstream
Pull the newest sources into the sibling checkout:
git -C ../greycat pull
Also read the upstream version — it is the source of truth for the SDK version string used later:
cat ../greycat/VERSION # e.g. 8.0
Part A — Upgrade the greycat Skill (copy)
The greycat skill is now maintained upstream at ../greycat/skills/ (a SKILL.md plus a
reference/ folder). Upgrading it is a straight copy into the plugin — no lib install, no
GCL syncing, no signature analysis.
Source: ../greycat/skills/
Destination: ./plugins/greycat/skills/greycat/
Clean the destination first (removes any renamed/deleted reference files), then copy the upstream skill in verbatim:
# Wipe old skill contents (keep the greycat/ dir itself)
rm -rf ./plugins/greycat/skills/greycat/reference
rm -f ./plugins/greycat/skills/greycat/SKILL.md
# Copy the upstream skill (SKILL.md + reference/*) into place
cp -r ../greycat/skills/. ./plugins/greycat/skills/greycat/
Verify the copy — the destination should mirror the source exactly:
diff -r ../greycat/skills/ ./plugins/greycat/skills/greycat/ && echo "greycat skill in sync"
Part B — Upgrade the greycat-c Skill (header analysis)
The greycat-c skill documents the native C SDK. Its source of truth is the upstream header tree, which is always at:
Headers: ../greycat/core/include/ (greycat.h + gc/*.h)
Destination docs: ./plugins/greycat-c/skills/greycat-c/
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.
- 2mo ago First seen · 164 lines · 16 tokens per session scan C fcbffa9d58de
update_greycat is a command published in the GitHub repository datathings/marketplace (11 stars, last pushed 11d ago), licensed Apache-2.0. It adds 16 tokens to every session and 1,512 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
update_greycat compared with commands from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| update_greycatdatathings/marketplace | Command | 11 | 11d ago | Apache-2.0 | C | 16 | Claude Code |
| merge-conflict-analysisrjmurillo/ai-agents | Command | 49 | yesterday | MIT | A | 0 | GitHub Copilot |
| release-notesOpenHands/extensions | Command | 176 | yesterday | MIT | A | 44 | Claude Code |
| commitechoVic/blade-code | Command | 181 | 24d ago | MIT | A | 8 | Claude Code |
| repo-audittractorjuice/arc-kit | Command | 2.3k | 2d ago | none | A | 29 | Claude Code |
| propsmill/infrahub-mcp | Command | 10 | yesterday | Apache-2.0 | A | 18 | Claude Code |
| codex-reviewoalders/kitchen-sink | Command | 5 | 4d ago | MIT | A | 41 | Claude Code |