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Creates, updates, or optimizes an AGENTS.md file for a repository with minimal, high-signal instructions covering non-discoverable coding conventions, tooling quirks, workflow preferences, and project-specific rules that agents cannot infer from reading the codebase. Use when setting up agent instru
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Content sha256 7b3af24c218956f5… — run codexguild_scan_skills after installing to verify your local copy.
Static analysis is a first line of defense, not a guarantee. Read the source
SKILL.md
When to use
Use this skill when creating or updating AGENTS.md for a repository.
Use it especially when:
- the current
AGENTS.mdis long, generic, or stale - agents repeatedly make the same avoidable mistakes
- repository workflows changed and agent guidance needs pruning
Instructions
Treat AGENTS.md as a living list of non-discoverable landmines and workflow gotchas, not a codebase overview.
Core rule: discoverability filter
Before adding any line, ask:
Can an agent discover this by reading the repo (
README, code, config, scripts, directory tree)?
- If yes: do not include it in
AGENTS.md. - If no, and it materially affects task success/cost/safety: include it.
What earns a line
Include only guidance that is:
- Non-discoverable from repository files alone
- Operationally significant (changes commands, outcomes, or safety)
- Actionable (specific enough to execute)
Typical examples:
- Non-standard tooling choices (e.g. use
uvinstead ofpip) - Command caveats (e.g. tests must run with
--no-cachedue to fixture behavior) - Hidden constraints/landmines (deprecated directories still imported in production)
- Critical local conventions that are not encoded in lint/tests/config
What to remove or avoid
Do not include:
- Tech stack summaries
- Directory structure overviews
- Architecture descriptions agents can infer from code
- Generic best-practice advice
- Rules already enforced by tooling (linters, typecheck, tests, CI)
- Mandatory boilerplate headers unless the repo explicitly requires one
Recommended structure
Prefer short, high-signal sections such as:
Scope & routing(which areas need separate/module-local AGENTS files)Non-discoverable commandsLandmines / do-not-touch areasTask-specific constraints
For large repos, recommend hierarchical AGENTS.md files near relevant modules instead of one monolithic root file.
Source files to check first
- Existing
AGENTS.md README.mdPROJECT.md(if present)- Cursor rules (
.cursor/rules/or.cursorrules) - Copilot instructions (
.github/copilot-instructions.md) GEMINI.md- CI/workflow files and package manager config (for command/tooling mismatches)
If AGENTS.md exists, improve it incrementally instead of replacing it blindly.
Maintenance mindset
AGENTS.md is temporary guidance, not permanent configuration.
When recurring issues appear:
- Prefer fixing the root cause in code/tooling (lint rule, test, script, structure)
- Keep only the minimum instruction needed until the root cause is solved
- Prune stale instructions aggressively
Quality gate before finalizing
For each line in AGENTS.md, verify:
- Is it non-discoverable?
- Is it still accurate today?
- Does it materially reduce mistakes/cost/time?
Delete any line that fails one of these checks.
Files
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