ForgeMCP: Instructions file for Codex

AGENTS.md

ForgeMCP AGENTS.md is an instructions file for Codex, OpenCode from hardened-steel/ForgeMCP. It costs 466 tokens per session, scanned A, original, MIT.

A set of instructions for ForgeMCP, a Python server that gives coding agents controlled tools for C++ work such as building, testing, and debugging.

In plain words
What is it for?
It helps agents work on ForgeMCP while following its documentation, module boundaries, workspace limits, type-annotation rules, and test requirements.
Why use it?
It gives agents project rules for architecture, file access, logging, and development practices, reducing the risk of unsafe or inconsistent changes.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md; mentions Codex.

This is hardened-steel/ForgeMCP's own configuration. It tells Codex and OpenCode how to work on ForgeMCP 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 ForgeMCP configures →

Reuse

Borrowing it

Nothing to install: this file belongs to hardened-steel/ForgeMCP. 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/hardened-steel/ForgeMCP/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/hardened-steel/ForgeMCP

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 ForgeMCP AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/hardened-steel/forgemcp/agents-md.svg)](https://agentmods.dev/instructions/hardened-steel/forgemcp/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/hardened-steel/forgemcp/agents-md"><img src="https://agentmods.dev/badge/instructions/hardened-steel/forgemcp/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 466 This file is loaded in full into every session.
When invoked 466 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 $0.00466 $0.00466
Opus 5 $0.00233 $0.00233
Sonnet 5 $0.00093 $0.00093
Haiku 4.5 $0.00047 $0.00047

Measured 3d ago against content hash a80c68b9825f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

ForgeMCP 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 3d 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 · 65 lines

How it starts

The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ForgeMCP agent guide

Project

ForgeMCP is a Python MCP server providing structured and safe C++ development capabilities: workspace operations, CMake/build/test, clangd integration, and native debugging.

Read first

Before designing or changing a module, read:

  1. README.md
  2. docs/architecture.md
  3. Relevant decisions in docs/adr/
  4. The tests closest to the module being changed

Architecture rules

  • src/forgemcp/core/ owns application composition, configuration, lifecycle, service registration, error conversion, and logging.
  • Core must not contain CMake, workspace, clangd, debugger, or process business logic.
  • New capabilities belong in separate modules and are registered through ServiceRegistry.
  • Domain models must be transport-neutral. Do not expose MCP, LSP, CMake, or DAP implementation types outside their adapters.
  • File access must remain scoped to the configured workspace.
  • Never write file contents or secrets to logs.

Development conventions

  • Python 3.11+; use type annotations for public APIs.
  • Prefer explicit dependencies over implicit global state.
  • Add or update unit tests for behaviour changes.
  • Keep MCP stdio output clean; operational logs go to stderr.
  • Do not change public contracts without documenting the decision in docs/adr/.

Validation

.\.venv\Scripts\python.exe -m pytest -q

Agents may run the following local, non-destructive workspace commands without additional confirmation:

npm run build --prefix frontend
npm test --prefix frontend
.\.venv\Scripts\python.exe -m pytest ...
.\.venv\Scripts\python.exe -m compileall ...
git diff --check

npm ci --prefix frontend may need network access when dependencies are first installed or the lockfile changes; any Codex sandbox approval for that command is a host-policy decision, not something this repository can disable.

Documentation ownership

Stable onboarding and rules: AGENTS.md Current system design: docs/architecture.md Rationale for irreversible decisions: docs/adr/ Work status and ordering: docs/roadmap.md

Read the full file on GitHub · 65 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. 3d ago Changed · +15 lines · +113 tokens per session a80c68b9825f
  2. 7d ago First seen · 50 lines · 353 tokens per session scan A 7e20c5117898

Subscribe to this mod's changes

ForgeMCP AGENTS.md is an instructions file published in the GitHub repository hardened-steel/ForgeMCP (0 stars, last pushed 2d ago), licensed MIT. It adds 466 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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