math-anchor: Instructions file for Codex

AGENTS.md

math-anchor AGENTS.md is an instructions file for Codex, OpenCode from tetracoralla/math-anchor. It costs 336 tokens per session, scanned A, original, Apache-2.0.

Repository instructions for Math Anchor, a tool for exact and scientific calculations, units, and dimensional analysis.

In plain words
What is it for?
Use them before reviewing or modifying Math Anchor's product behavior, parser, calculation core, MCP tools, validation, or error handling.
Why use it?
They define which product documents to read and the safety rules to follow when reviewing or changing the product.

Instructions file for CodexOpenCode

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

This is tetracoralla/math-anchor's own configuration. It tells Codex and OpenCode how to work on math-anchor 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 math-anchor configures →

Reuse

Borrowing it

Nothing to install: this file belongs to tetracoralla/math-anchor. 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/tetracoralla/math-anchor/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/tetracoralla/math-anchor

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 math-anchor AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/tetracoralla/math-anchor/agents-md/github.svg)](https://agentmods.dev/instructions/tetracoralla/math-anchor/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/tetracoralla/math-anchor/agents-md"><img src="https://agentmods.dev/badge/instructions/tetracoralla/math-anchor/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.

agentmods 80×15 button for math-anchor AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/tetracoralla/math-anchor/agents-md"><img src="https://agentmods.dev/badge/instructions/tetracoralla/math-anchor/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 336 This file is loaded in full into every session.
When invoked 336 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 $0.00336 $0.00336
Opus 5.5 $0.00134 $0.00134
Sonnet 5.5 $0.00067 $0.00067
Haiku 4.5 $0.00034 $0.00034

Measured 1mo ago against content hash ac3434cb4e63, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

math-anchor 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.

AGENTS.md · 20 lines

What it actually says

Math Anchor repository contract

Read docs/product-model.md and docs/REVIEW_CONTRACT.md before changing or reviewing the product surface.

For a requested review, read docs/REVIEW_CONTRACT.md within the requested scope and follow the relevant source and dependencies. It records known risks, not an exhaustive search plan. Report concrete cross-repository implications when found. Review is read-only unless fixes are also requested; this entrypoint does not dispatch another reviewer.

  • Keep the human macOS app and the Agent interface on one calculation core.
  • Keep Agent discovery, schemas, runtime metadata, and protocol concepts out of the human calculator UI.
  • Keep the public MCP surface to math.search, math.describe, math.run, and math.batch; add capabilities to the operation registry, not as more public tools.
  • Never evaluate input with Python eval, exec, string sympify, or parse_expr. Extend the explicit AST translator when new expression syntax is required.
  • Preserve exact and approximate results as separate fields. Never label a floating approximation as exact.
  • Add a negative regression test for parser, validation, timeout, and error-path fixes.
  • Treat mathematical semantics, parser/schema alignment, internal bounds, error codes, refactors, tests, packaging, and runtime verification as Agent-owned technical closure. Decide from current source and executable behavior; do not ask the owner to choose among implementation details. Ask only for a plain-language product-direction or external-authorization decision.
  • Report development regression, MCP/runtime user flow, and human experience acceptance separately.
  • Do not commit or push unless the owner explicitly asks.
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. 1mo ago Changed · -8 tokens per session ac3434cb4e63
  2. 2mo ago First seen · 20 lines · 344 tokens per session scan A f8e6c1e4290e

Subscribe to this mod's changes

math-anchor AGENTS.md is an instructions file published in the GitHub repository tetracoralla/math-anchor (0 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 336 tokens to every session, about $0.0013 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 2026-08-31.

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