filesystem-mcp: Instructions file for Codex

AGENTS.md

filesystem-mcp AGENTS.md is an instructions file for Codex, OpenCode from SylphxAI/filesystem-mcp. It costs 455 tokens per session, scanned A, original, MIT.

A project-specific instruction file for the filesystem-mcp repository. It records local rules about the filesystem server, commands, security boundaries, validation, and release work.

In plain words
What is it for?
Use it when working on filesystem-mcp to find the expected commands, validation checks, release boundaries, and sources of project truth.
Why use it?
It gives a coding agent repository context and warns about risks such as unsafe paths and mixing different publishing changes.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md.

This is SylphxAI/filesystem-mcp's own configuration. It tells Codex and OpenCode how to work on filesystem-mcp itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything filesystem-mcp configures →

Reuse

Borrowing it

Nothing to install: this file belongs to SylphxAI/filesystem-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/SylphxAI/filesystem-mcp/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/SylphxAI/filesystem-mcp

Made for: Codex, OpenCode.

Wrote 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.

agentmods badge for filesystem-mcp AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/sylphxai/filesystem-mcp/agents-md.svg)](https://agentmods.dev/instructions/sylphxai/filesystem-mcp/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/sylphxai/filesystem-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/sylphxai/filesystem-mcp/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 455 This file is loaded in full into every session.
When invoked 455 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00455 $0.00455
Opus 5 $0.00228 $0.00228
Sonnet 5 $0.00091 $0.00091
Haiku 4.5 $0.00046 $0.00046

Measured 7d ago against content hash f063819ef83d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

filesystem-mcp 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 7d 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.md · 45 lines

How it starts

The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.

filesystem-mcp — local agent notes only

Static engineering and delivery standards load from the active Skills runtime (SylphxAI/skills is binding instruction SSOT). Doctrine and Mission Control are retired historical lineage and must not be loaded as current instruction authority.

Local truth: PROJECT.md, .doctrine/project.json when present.

Boundary hazards

  • This is a security-sensitive MCP filesystem server. Path confinement, batch
  • Release workflows publish npm, Docker Hub images, GitHub releases, and docs.
  • Do not mix package/image publishing changes with docs/control-plane changes.

Local commands

  • pnpm install --frozen-lockfile - install dependencies.
  • pnpm run validate - formatting, lint, typecheck, and tests.
  • pnpm run build - build package artifacts.
  • pnpm run docs:build - build documentation.
  • Prefer the narrowest affected check before full workspace runs.
  • Report layers honestly: local diff · trunk FF · deploy · prod proof (do not collapse).

Validation notes

  • Prefer the narrowest affected check before full workspace runs.
  • Report layers honestly: local diff · trunk FF · deploy · prod proof (do not collapse).

Backend false-authority fence

Work: wi_01KYFN6993PMG8WD00Q51AE231

If this repository has completed a Rust backend cutover:

  1. Production backend behavior authority is the Rust crate/binary/service path declared in sylphx.toml / deploy manifests / package bin native path / Docker ENTRYPOINT.
  2. Residual TypeScript service trees or alternate TS engines are not product authority unless explicitly proven still on the live path.
  3. Do not "fix production" by editing residual TypeScript and assuming deploy/runtime will pick it up.
  4. Prefer deleting residual TS backend trees after Rust sole proof; keep history in Git.
  5. Intentional TypeScript frontends, npm packaging wrappers, and native-binding surfaces may remain.

Repo-specific note

Rust binary is runtime authority; TS/npm packaging is not an alternate backend implementation.

Read the full file on GitHub · 45 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. 7d ago First seen · 45 lines · 455 tokens per session scan A f063819ef83d

Subscribe to this mod's changes

filesystem-mcp AGENTS.md is an instructions file published in the GitHub repository SylphxAI/filesystem-mcp (8 stars, last pushed 1mo ago), licensed MIT. It adds 455 tokens to every session, about $0.0023 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 2026-08-31.

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