agents-md

A tool for creating or updating AGENTS.md files, which are instruction files that tell AI coding agents how to work in a project or folder.

In plain words
What is it for?
Use it to document project structure, commands, coding style, testing, security guidance, and folder-specific rules.
Why use it?
It keeps agent guidance accurate, short, and located where it is most useful instead of leaving agents without project-specific instructions.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/agent-substrate/substrate/agents-md
Any agent
npx skills add agent-substrate/substrate --skill agents-md
Clone the repo
git clone --depth 1 https://github.com/agent-substrate/substrate

Made for: Claude Code, Codex.

Per session 12 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 545 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00012 $0.00545
Opus 5 $0.00006 $0.00272
Sonnet 5 $0.00002 $0.00109
Haiku 4.5 $0.00001 $0.00055

Measured 2d ago against content hash b9effdec783f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agents-md 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 2d 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.

.agents/skills/agents-md/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Generate or update AGENTS.md files in key folders of the project. Ensure the target AGENTS.md file accurately reflects the current status of the code.

Key Requirements

There must always be an AGENTS.md file in the project root. The AGENTS.md file at the root of the project may include the following sections:

  • Project overview
  • Build and test commands
  • Code style guidelines
  • Testing instructions
  • Security considerations

AGENTS.md files in subfolders may be even more concise and specific to those subfolders.

Maximize AGENTS.md Performance

To maximize agent performance and token efficiency, adhere to the following:

Progressive Disclosure

Each AGENTS.md should be short. Approx. 100-150 lines total. Link to a handful of relevant, focused reference documents in the same repo, as needed.

Modularity

While only one AGENTS.md is allowed per folder, you can create an AGENTS.md file in any folder. Rather than putting everything in the root AGENTS.md, move highly specific advice to AGENTS.md in the most relevant folders of the project.

References

When documentation that would have helped you is missing, add references in the docs/ folder found at the project root. When these get out of date, update them.

Workflows

When references describe workflows, the tasks should be described as numbered steps. For example:

  1. Get the beep from the boop.
  2. Then bop it.

Decisions

When there are multiple ways of doing something in the codebase, use a decision table like the following:

Question Boop Bop
Is foo a bar baz?
Is foo a quux?

Real Code Examples

If you think they are particularly good examples, include snippets from actual code in the repo, up to approx. 10 lines in length. These should only be the most relevant examples and representative of patterns that would be good to repeat in future code. Their purpose is to improve code reuse by agents, rather than each agent reinventing the wheel.

Read the full file on GitHub · 72 lines

Changes

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.

  1. 2d ago First seen · 72 lines · 12 tokens per session scan A b9effdec783f

Subscribe to this mod's changes

agents-md is a skill published in the GitHub repository agent-substrate/substrate (1,645 stars, last pushed 2d ago), licensed Apache-2.0. It adds 12 tokens to every session and 545 once invoked, about $0.0001 per session on Opus 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.

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