What is MetaSpec AGENTS.md?

A guide for MetaSpec, a framework that creates toolkits from formal specifications. These toolkits can support development, design, testing, documentation, or operations.

Creating speckits, defining rules for a domain, and working with MetaSpec's command-line tools, parsers, validators, templates, and agent support.

It explains the concepts and commands an AI agent needs when creating or using a specification-based toolkit.

How acnlabs/MetaSpec configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to acnlabs/MetaSpec. 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/acnlabs/MetaSpec/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/acnlabs/MetaSpec

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/acnlabs/metaspec/agents-md/github.svg)](https://agentmods.dev/instructions/acnlabs/metaspec/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/acnlabs/metaspec/agents-md"><img src="https://agentmods.dev/badge/instructions/acnlabs/metaspec/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/acnlabs/metaspec/agents-md"><img src="https://agentmods.dev/badge/instructions/acnlabs/metaspec/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 12,090 This file is loaded in full into every session.

When invoked 12,090 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.

Model	Per session	Once invoked
Fable 5.1	$0.12090	$0.12090
Opus 5.5	$0.04836	$0.04836
Sonnet 5.5	$0.02418	$0.02418
Haiku 4.5	$0.01209	$0.01209

Measured 2mo ago against content hash 81944f8fce3c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

MetaSpec 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 2mo 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 · 1,422 lines

How it starts

The opening of the file, as written. The whole thing — 1,422 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Meta-Spec AI Agent Guide

For AI Assistants: This document provides guidance on using Meta-Spec to generate Spec-Driven X (SD-X) speckits.

🎯 Your Role

You are helping a developer create speckits (spec-driven toolkits for AI agents) using MetaSpec.

MetaSpec is a meta-specification framework that generates complete Spec-Driven X (SD-X) speckits:

SD-Development - Spec-driven development
SD-Design - Spec-driven design systems
SD-Testing - Spec-driven testing frameworks
SD-Documentation - Spec-driven documentation
SD-Operations - Spec-driven operations
SD-X - Spec-driven generation for any domain

Key principle: MetaSpec generates production-ready speckits with CLI, parser, validator, templates, and AI agent support

💡 Core Concept: Meta-Specification Framework

MetaSpec is a meta-specification framework - it uses specifications to generate specification toolkits.

Meta-Specification (MetaSpec)
        ↓
  Defines how to define specifications
        ↓
Generates Speckits (Spec-driven Toolkits)
        ↓
Speckits carry domain specifications
        ↓
Used to develop domain projects

Key Insights

Meta-level abstraction - MetaSpec defines how to create specification systems
Generative framework - Generates complete speckits from meta-specifications
Recursive architecture - MetaSpec uses SDD to develop itself, generates speckits that use SDD
Specification-centric - Domain specs are the source of truth, speckits are carriers

Example Flow:

MetaSpec (meta-spec)
    ↓ generates
MCP-Spec-Kit (carries MCP specification spec)
    ↓ used by
Developer (validates MCP servers against spec)

This means: MetaSpec is not just "spec-driven development" - it's a framework that generates speckits (spec-driven toolkits) for any domain.

See Recommended Practice: SDS + SDD Separation in MetaSpec Commands section for how speckits separate domain specifications from toolkit implementation.

Read the full file on GitHub · 1,422 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.

2mo ago First seen · 1,422 lines · 12,090 tokens per session scan A 81944f8fce3c

Subscribe to this mod's changes

MetaSpec AGENTS.md is an instructions file published in the GitHub repository acnlabs/MetaSpec (54 stars, last pushed 11mo ago), licensed MIT. It adds 12,090 tokens to every session, about $0.0484 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.

Building agents ai intent spec spec-driven

MetaSpec AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
MetaSpec AGENTS.mdacnlabs/MetaSpec	Instructions file	54	11mo ago	MIT	A	12,090	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	yesterday	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

MetaSpec: Instructions file for Codex