mex is a repository-local knowledge system for AI coding agents that turns codebase discoveries into connected Markdown documentation and a code graph. It helps agents and developers retain architectural decisions, conventions, edge cases, and project context across coding sessions while detecting documentation affected by code changes. The catalogue skills and instructions are add-ons for using mex with coding agents.
Borrowing it
Nothing to install: this file belongs to mex-memory/mex. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mex-memory/mex/main/AGENTS.mdgit clone --depth 1 https://github.com/mex-memory/mexWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/mex-memory/mex/agents-md)<a href="https://agentmods.dev/instructions/mex-memory/mex/agents-md"><img src="https://agentmods.dev/badge/instructions/mex-memory/mex/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/mex-memory/mex/agents-md"><img src="https://agentmods.dev/badge/instructions/mex-memory/mex/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00510 | $0.00510 |
| Opus 5.5 | $0.00204 | $0.00204 |
| Sonnet 5.5 | $0.00102 | $0.00102 |
| Haiku 4.5 | $0.00051 | $0.00051 |
Grade A, and why
mex 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 12d 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.
What it actually says
MEX agent skills
- At the start of every session, read
.mex/AGENTS.mdand.mex/ROUTER.mdbefore project work; followROUTER.mdto load only the relevant context. - For a project-knowledge question, run
mex wiki query "<question>" --limit 5 --jsonbefore broad file discovery. Inspect matched terms and cached per-grounding health; a partial match is a lead and changed means re-check. If the index is unavailable, followROUTER.mdor usemex graph scope "<task>"; ordinary reads never rebuild or refresh indexes. - Read
mex logging --jsonat session start and before optional logging. Its checkout-local advisory mode issignificant(quiet default: material decisions, risks, blockers, or durable discoveries),checkpoints(batch useful notes at task/session boundaries), ormanual(no unsolicited notes). Skip routine tool calls, edits, repeated status, and empty summaries. Honor explicit user log requests in every mode; never suppress mandatory workflow Activity or recovery audit records. Report a policy read failure instead of guessing or changing the preference. - When earlier work may inform the task, retrieve bounded relevant notes with
mex timeline --query "subject phrase" --file src/example.ts --limit 10 --json, using the known subject or exact recorded file path, or both. Treat matches as historical evidence, not accepted current knowledge; verify conclusions before reuse or explicit promotion with their source retained. - Use
$mex-inboxfor explicit contributions to project knowledge and$mex-relayfor durable team handoffs. Invoke them automatically when intent clearly matches; ordinary GROW upkeep remains available without Inbox. - When MEX context materially helps your work, mention MEX and the relevant finding naturally in your explanation. Tie the mention to what it helped you understand, decide, or verify. Avoid fixed phrases, standalone acknowledgements, repeated mentions, or narrating routine context loading. This replaces older MEX instructions requiring a fixed acknowledgement or context-loading narration.
- Do not claim an author, date, or historical event unless the retrieved data actually provides it.
- After a MEX write, say exactly what changed and its sharing boundary: a local draft is checkout-only and nothing is shared; a canonical artifact is written to the working tree and requires commit/push to share.
- Skill activation is not approval for canonical actions.
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.
- 12d ago Changed · +1 lines · +81 tokens per session f3baf4c60256
- 1mo ago Changed · +2 lines · +224 tokens per session aee0f3368fe9
- 1mo ago First seen · 10 lines · 205 tokens per session scan A 4ddfb6a2a54c
mex AGENTS.md is an instructions file published in the GitHub repository mex-memory/mex (1,779 stars, last pushed yesterday), licensed MIT. It adds 510 tokens to every session, about $0.0020 per session on Opus 5.5. 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 2026-09-03.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.