mcm-o-guide

From the files and frontmatter at commit d407c48. This is how much a skill can do, not whether it is risky.

• Runs shell commands

  Its instructions or files give the agent commands to run on your computer.

• Reaches the network

  It sends or fetches data over the internet, for example with curl, an HTTP library or a package install.

• Names web addresses

  It mentions outside web addresses the agent may visit. We list them but don't follow them.

  Outside links we did not follow

• Bundles scripts

  The folder holds code files the agent may run.

  scripts/benchmark-paper.mjs (opens in a new tab) · scripts/check-paper.mjs (opens in a new tab) · scripts/extract-pdf.mjs (opens in a new tab) and 1 more

Pattern check: nothing flagged · commit d407c48 · 31 Oct 2026

We checked every text file in this skill, at commit d407c48 on 31 Oct 2026, against 45 published patterns such as download-and-run commands, hidden text and credential access. We don't run the skill, we don't read the web pages it points to, and we can't judge everything its instructions might lead an agent to do. In published tests, pattern checks like this one missed most malicious skills. Read the skill before you install it — especially anything it asks you to download or run.

How the check worksReport an incorrect finding

Each agent reads SKILL.md a little differently. We check the file against each one's published rules; we don't run the skill in any agent.

• Agent Skills specPasses with warnings

  The open format from agentskills.io, held to what the strictest agents enforce, so one folder loads everywhere.

  • Warning

    Fields outside the spec: category. Uploads to the Claude apps and API, and the spec's validator, reject the file; most agents ignore these fields. O1

    Fix: Delete them for a portable skill, or keep them if you only target the agents that read them.

  • Note

    The description doesn't say when to use the skill. D6

    Fix: Add a sentence such as "Use when …" naming the requests or files that should trigger it.

  • Note

    There is no license field, so readers can't tell whether they may reuse the skill. O2

    Fix: Add license: with an SPDX name such as MIT or Apache-2.0, or the name of a bundled licence file.

  • Note

    Reference files that SKILL.md doesn't link: GUIDE.en.md. Anthropic suggests linking every reference file directly from SKILL.md. B4

    Fix: Link each one from SKILL.md and say when to read it.

  • Note

    Reference files over 100 lines with no table of contents at the top: GUIDE.en.md (158 lines), SKILL.en.md (478 lines), playbooks/coding-playbook.md (462 lines), playbooks/modeling-playbook.md (400 lines), playbooks/research-playbook.md (337 lines) and 23 more. B5

    Fix: Add a short list of the sections at the top of each.

• Claude CodePasses

  Claude Code reads its own extra fields, ignores unknown ones, and still loads a skill whose frontmatter is broken, without its fields.

  • Note

    Claude Code ignores fields it doesn't know: category. O1

    Fix: Check the spelling against Claude Code's field list, or delete them.

  • Note

    Reference files that SKILL.md doesn't link: GUIDE.en.md. Anthropic suggests linking every reference file directly from SKILL.md. B4

    Fix: Link each one from SKILL.md and say when to read it.

  • Note

    Reference files over 100 lines with no table of contents at the top: GUIDE.en.md (158 lines), SKILL.en.md (478 lines), playbooks/coding-playbook.md (462 lines), playbooks/modeling-playbook.md (400 lines), playbooks/research-playbook.md (337 lines) and 23 more. B5

    Fix: Add a short list of the sections at the top of each.

• Claude apps & API uploadFails

  Uploading to claude.ai or the Claude API, or packaging with Anthropic's script, accepts only the six spec fields and stops on anything else.

  • Error

    Upload and packaging fail on fields outside the spec: category. O1

    Fix: Delete them, and keep your own data under metadata as text values.

  • Note

    Reference files that SKILL.md doesn't link: GUIDE.en.md. Anthropic suggests linking every reference file directly from SKILL.md. B4

    Fix: Link each one from SKILL.md and say when to read it.

  • Note

    Reference files over 100 lines with no table of contents at the top: GUIDE.en.md (158 lines), SKILL.en.md (478 lines), playbooks/coding-playbook.md (462 lines), playbooks/modeling-playbook.md (400 lines), playbooks/research-playbook.md (337 lines) and 23 more. B5

    Fix: Add a short list of the sections at the top of each.

• OpenAI (Codex & API)Passes with warnings

  Codex finds SKILL.md by its exact name and needs a description; OpenAI's Skills API checks the frontmatter against the spec and caps uploads.

  • Warning

    Fields outside the spec: category. Codex ignores them; OpenAI doesn't say whether its upload accepts them. O1

    Fix: Delete them, or move your own data under metadata as text values.

• VS Code & CopilotPasses

  VS Code reads skills one folder below .github/skills, .claude/skills or .agents/skills and falls back to the folder name when the name is missing or differs; GitHub's Copilot docs require the exact name SKILL.md.

  • Note

    VS Code ignores fields it doesn't support: category. O1

    Fix: Delete them unless another agent you target reads them.

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