Borrowing it
Nothing to install: this file belongs to tallclub/matimo. 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/tallclub/matimo/main/.github/skills/tool-creation/SKILL.mdgit clone --depth 1 https://github.com/tallclub/matimoWrote 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/tallclub/matimo/tool-creation)<a href="https://agentmods.dev/skills/tallclub/matimo/tool-creation"><img src="https://agentmods.dev/badge/skills/tallclub/matimo/tool-creation/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/tallclub/matimo/tool-creation"><img src="https://agentmods.dev/badge/skills/tallclub/matimo/tool-creation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 7 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Anti-Refusal · line 844 Skill instructs the agent to omit warnings, disclaimers, or ethical commentary. Stripping safety caveats hides risk from the user and is a common jailbreak preamble.Fix: Remove instructions that suppress warnings, disclaimers, or ethical commentary. Let the agent surface safety-relevant caveats to the user.
- medium Excessive Agency · line 21 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
- medium Data Exfiltration · line 121 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 160 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 991 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 252 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Excessive Agency · line 896 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 | $0.00038 | $0.02973 |
| Opus 5.5 | $0.00015 | $0.01189 |
| Sonnet 5.5 | $0.00008 | $0.00595 |
| Haiku 4.5 | $0.00004 | $0.00297 |
Grade A, and why
tool-creation 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 — 307 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Tool Creation for Matimo SDK
This is the repository copy of the core
tool-creationskill shipped intypescript/packages/core/skills/tool-creation/SKILL.md. Keep the two in sync.
This skill teaches you how to write a correct Matimo tool definition: one YAML file that runs the same way from the SDK, LangChain, CrewAI and MCP.
Two audiences — know which one you are:
You are an agent at runtime You are an SDK developer Creating tools with matimo_create_toolAdding tools to the codebase Tools go to <target_dir>/<tool-name>/definition.yaml(default./matimo-tools)Tools go to packages/<provider>/tools/<tool-name>/definition.yamlValidate with matimo_validate_toolValidate with pnpm validate-toolsOnly type: http; a human approves every toolhttp,functionorcommand; reviewed in a pull requestIf you are an agent, follow the agent column. The SDK developer sections are marked.
How a Tool Runs
definition.yaml
↓ loaded and checked against the schema
Tool registry
↓ matimo.execute(name, params)
Policy: risk level, execution gates, optional HITL quarantine
↓
Approval: a human is asked if the tool requires it
↓
Credentials filled into {PLACEHOLDERS}
↓
Executor: http | function | command
↓
Response size cap, then the result is returned
Matimo does not check parameters against your parameters: block before running, and does not check the response against output_schema. The API you call reports bad input; write clear parameter descriptions so the caller sends the right values.
Agent Lifecycle
matimo_validate_tool(yaml_content) ← 1. valid: true means create will accept it
matimo_create_tool(name, yaml_content, target_dir)
↓ writes <target_dir>/<name>/definition.yaml
↓ sets requires_approval: true and status: draft
matimo_reload_tools() ← 2. registers the draft (it cannot run yet)
matimo_approve_tool(name, tool_dir) ← 3. a human approves it
matimo_reload_tools() ← 4. the approved tool is live
<tool name>(params) ← 5. each call still asks a human
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 Changed · -865 lines 1edf517f1412
- 2mo ago First seen · 1,172 lines · 38 tokens per session scan A b7c13c0150bb
tool-creation is a skill published in the GitHub repository tallclub/matimo (18 stars, last pushed yesterday), licensed MIT. It adds 38 tokens to every session and 2,973 once invoked, about $0.0002 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 2026-08-30.
tool-creation compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| tool-creationtallclub/matimo | Skill | 18 | yesterday | MIT | A | 38 | Claude Code, Codex |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 103 | Claude Code |