Agent Skill Instruction Creation

Agent Skill Instruction Creation

Use this skill to create agent-facing instructions that are grounded in the target project, not generic prompt prose. Prefer the smallest durable surface that matches the requested scope.

Source Priority

• For Codex behavior, verify current OpenAI Codex docs or the Codex manual when discovery, precedence, or supported surfaces matter.
• For portable Agent Skills, verify the current Agent Skills specification when frontmatter, folder layout, bundled resources, or trigger behavior matter.
• For this repository or another skill package, obey repo-local validators and schemas even when the broader Agent Skills specification allows additional fields.
• Treat third-party gists, blog posts, and examples as advisory. Use them for ideas, not as authority over official docs or repo rules.

Choose The Surface

• Use AGENTS.md for durable repository conventions, setup commands, validation expectations, review priorities, and local workflow rules.
• Use nested AGENTS.md or AGENTS.override.md files when a subdirectory needs different commands, constraints, generated-code rules, or ownership boundaries.
• Use fallback names such as CLAUDE.md, .github/copilot-instructions.md, Cursor rules, or configured project-doc filenames only when the target agent or existing repo convention requires them.
• Use a skill when the user needs a reusable task workflow with procedural knowledge, optional scripts, references, or assets.
• Use a plugin when distribution needs more than a local skill folder, such as bundled skills plus apps, MCP configuration, hooks, or install metadata.
• Do not create an agent instruction file to store secrets, credentials, private tokens, or one-off task notes.

Discovery Workflow

1. Identify the target agent clients and current discovery rules before creating files.
2. Inspect package metadata, lockfiles, build scripts, CI workflows, test directories, docs, existing style configs, security tooling, deployment notes, and generated-file patterns.
3. Ask only when the repo cannot answer a durable decision, such as team policy, preferred validation gates, publishing intent, or whether guidance should apply globally or to one subtree.
4. Draft from project evidence: exact commands, paths, package manager, module boundaries, review expectations, and failure recovery steps.
5. Keep instructions compact and procedural. Avoid broad persona text, duplicated README content, and generic "be careful" guidance.

AGENTS.md Creation

Create plain Markdown with headings that fit the project. Codex loads applicable AGENTS.md guidance automatically, and more specific files closer to the working path can specialize broader guidance. Keep global, repo, and subtree guidance separate instead of repeating the same rules everywhere.

Common sections:

• Repository purpose and boundaries.
• Setup, build, test, lint, typecheck, format, and release commands.
• Code style, architecture, generated-file, dependency, and migration rules.
• Security, secrets, data handling, network, destructive-command, and permission boundaries.
• Review guidelines with project-specific P0/P1 risks.
• Validation expectations and what to do when commands are slow, unavailable, or flaky.

Make commands copy-pasteable and real. Mention nested precedence only when the repo has or needs nested instruction files.

Do not use AGENTS.md for one-off task notes, secrets, credentials, private tokens, large copied logs, generated API docs, or broad motivational guidance. If a rule is repeated because an agent made the same mistake, rewrite it as a short trigger, decision rule, or command.

Skill Creation

Create skills as small folders with a required SKILL.md, plus optional scripts/, references/, assets/, and agents/openai.yaml when the target client uses it.

1. Name the skill with lowercase hyphen-case and match the folder name.
2. Put only name and description in frontmatter unless the target repository explicitly allows broader Agent Skills metadata.
3. Write the description for triggering: front-load user intent, include realistic trigger words, define boundaries, and avoid claiming adjacent tasks.
4. Write the body as a reusable workflow using imperative steps, source-of-truth rules, validation loops, gotchas, and output expectations.
5. Keep SKILL.md compact. Add references only for bulky or variant-specific material that should load on demand, and link each reference from SKILL.md with when to read it.
6. Add scripts only for deterministic repeated logic, and make them self-contained with clear dependencies and error messages.
7. Add assets only when the skill needs templates, icons, fonts, sample files, or other output resources.
8. Add trigger eval prompts or forward tests for complex skills when practical, including near-miss prompts that should not trigger.
9. Avoid embedding whole old prompts or copied documentation. Distill them into durable procedures, checklists, and source links.

Validation

• Run repo-local validation first, such as npm run validate, markdown lint, schema checks, or generator scripts.
• Use repo-local skillcheck wrappers first, such as npm run skillcheck; otherwise use skillcheck directly to check SKILL.md format, references, description quality, sizing, semantic graph relationships, and cross-agent compatibility. Read skillcheck-config.md before adding a strict skillcheck.toml or using --semantic.
• Use npx agentlinter when available to score AGENTS.md/CLAUDE.md-like workspaces for clarity, completeness, security, and consistency.
• For Codex skills, verify agents/openai.yaml against the current SchemaStore/OpenAI metadata shape when that file is present.
• If the new instruction surface changes expected behavior materially, sanity-test it with realistic prompts or a fresh Codex run when practical.

Output

Finish with files created, why each surface belongs at that scope, commands run, and any policy choices the user still needs to decide.