Borrowing it
Nothing to install: this file belongs to webern/mx. 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/webern/mx/main/AGENTS.mdgit clone --depth 1 https://github.com/webern/mxWrote 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/webern/mx/agents-md)<a href="https://agentmods.dev/instructions/webern/mx/agents-md"><img src="https://agentmods.dev/badge/instructions/webern/mx/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/webern/mx/agents-md"><img src="https://agentmods.dev/badge/instructions/webern/mx/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 | $0.02631 | $0.02631 |
| Opus 5.5 | $0.01052 | $0.01052 |
| Sonnet 5.5 | $0.00526 | $0.00526 |
| Haiku 4.5 | $0.00263 | $0.00263 |
Grade A, and why
mx 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 190 lines — stays where its author put it; the contents beside it link to each section on GitHub.
mx
@./README.md
mx is a MusicXML C++ library. The product surface is mx::api, a simplified and narrowed
interface of MusicXML backed by the strongly-typed mx::core model.
Quickstart: make core-roundtrip-test (fast corert gate) - make fmt (format) - make help (all
targets). Everything runs in the mx-sdk Docker image unless MX_RUNNING_IN_DOCKER=1.
Repository layout
mx/
AGENTS.md <- you are here
.claude/skills/ <- agent skills; every skill name starts with mx-
Makefile <- top-level build driver
Dockerfile <- mx-sdk image with toolchains and dev tools
CMakeLists.txt <- C++ project
Package.swift <- Swift Package Manager wrapper (built by the swift CI job)
data/ <- MusicXML test corpus (large, see data/README.md)
docs/ai/design/ <- design docs
docs/musicxml-4.0-ed15c23.xsd <- the current musicxml.xsd schema
src/ <- C++ sourcecode root
src/include/mx/api/ <- the public mx::api headers; mx's public interface
src/private/ <- C++ source
pugixml/ <- vendored pugixml 1.15 (XML parser and raw DOM)
mx/core/ <- mx::core's hand-written runtime (outside of mx/core/generated)
mx/core/generated/ <- MusicXML XSD C++ typed model (generated, see gen/cpp)
mx/api/ <- mx::api implementation
mx/impl/ <- the api to core translation layer
mx/utility/ <- helpers
mx/examples/ <- api example programs
mxtest/core/ <- mx::core unit tests (small)
mxtest/corert/ <- C++ core roundtrip test (deserializes and serializes the test corpus)
mxtest/import/ <- normalization support (Normalize.cpp/h + DecimalFields.h) shared by corert and api tests
mxtest/api/ <- tests for the mx::api layer
mxtest/impl/ <- tests for the mx::impl layer
mxtest/file/ <- file-walking test infrastructure for the mx::api tests (MxFile, MxFileTest, etc.)
mxtest/control/ <- compile-control flags (CompileControl.h: enables/disables test suite compilation)
cpul/ <- vendored Catch2 test runner
gen/ <- code generator system (see gen/README.md)
cpp/ <- C++ target (the product): config.toml + templates
schema/ <- JSON Schema target
test/go/ <- A toy Go implementation of MusicXML XSD for gen validation
test/c/ <- A toy C implementation of MusicXML XSD for gen validation
audit/ <- MusicXML feature-audit tool (see audit/README.md); `make audit`
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.
- 1mo ago Changed · +6 tokens per session 0b329dfeb37b
- 2mo ago First seen · 190 lines · 2,625 tokens per session scan A 3cf5a5c87252
mx AGENTS.md is an instructions file published in the GitHub repository webern/mx (93 stars, last pushed yesterday), licensed MIT. It adds 2,631 tokens to every session, about $0.0105 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 2026-08-30.
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).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.