MCPs, plugins, and skills

Use the right extension mechanism

Mechanism	Owner	Supplies	Reconcile/check
MCP registry	mcp-servers.txt	endpoint, profile, risk, auth reference	bash install/codex.sh sync-config; check
Codex plugins	codex-plugins.txt	marketplace inventory	bash install/codex.sh sync-config / check
Claude plugins	claude-plugins.txt	plugins, commands, agents, or skills	bash install/claude.sh install
Installer skills	agent-skills.txt	shared skill receipts/digests	bash install/skills-sync.sh check
Repository skills	home/dot_claude/skills/	versioned procedures/assets	chezmoi apply

Configured capability is not a successful login, live endpoint, or authority to mutate an external system.

Preserve the one-owner rule

A skill belongs either in packages/agent-skills.txt or home/dot_claude/skills/, never both. The deployed tree is ~/.claude/skills, linked as ~/.agents/skills for Codex, OpenCode, and Pi.

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bash install/skills-sync.sh check is read-only. Do not use npx skills check as an audit: it may update installed skills.

Add an MCP deliberately

chrome-devtools stdio profile=browser risk=external-write cmd: npx -y [email protected] --no-usage-statistics --no-performance-crux

That line declares transport, profile, risk, and command. It does not start Chrome or grant an account permission. Read the registry header and install/codex.sh, regenerate configuration, start a new task, inspect its tools, and exercise a harmless read when supported.

Plugin inventory is separate

Codex entries use PLUGIN@MARKETPLACE. The installer distinguishes missing/disabled declarations from unavailable upstream items. Do not make an unlisted local install permanent; declare it through its approved owner. Claude marketplace coupling is documented in claude-plugins.txt. See cross-harness agent guidance.

Credentials and authority remain separate

Registry auth names (gh, Google ADC relay, or environment-variable references) are not a credential vault. Use authentication setup, test a fresh session, and keep secret exports outside the repository. Remote writes, purchases, consent, OS privacy, and MFA remain external boundaries.