calculate

calculate is a skill for Codex from tetracoralla/math-anchor. It costs 83 tokens per session (1,123 once invoked), scanned A, original, Apache-2.0.

A set of instructions for choosing when to use Math Anchor, a mathematics tool, for exact or reliability-sensitive calculations.

In plain words
What is it for?
It is for routing mathematical requests to the right calculation method and checking results involving exact arithmetic, matrices, units, statistics, probability, finance, or machine-number rules.
Why use it?
It helps prevent mistakes in cases such as computer-number formats, bit operations, large counts, and high-precision results.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit It is for routing mathematical requests to the right calculation method and checking results involving exact arithmetic, matrices, units, statistics, probability, finance, or machine-number rules.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tetracoralla/math-anchor/calculate
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add tetracoralla/math-anchor --skill calculate
Clone the repo
git clone --depth 1 https://github.com/tetracoralla/math-anchor

Made for: Codex.

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 calculate

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/tetracoralla/math-anchor/calculate"><img src="https://agentmods.dev/badge/skills/tetracoralla/math-anchor/calculate.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,123 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00083 $0.01123
Opus 5 $0.00042 $0.00562
Sonnet 5 $0.00017 $0.00225
Haiku 4.5 $0.00008 $0.00112

Measured 6d ago against content hash 5ce24ddbcf25, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

calculate 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 6d 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.

plugins/math-anchor/skills/calculate/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Calculate

Decide and route

  • Do not load it for trivial, low-risk arithmetic the model can immediately verify.
  • Treat fixed-width wrapping/saturating arithmetic as mandatory; do not classify them as trivial arithmetic.
  • Always use it for fixed-width or IEEE-754 facts, exact/high-precision or symbolic work, matrices, units, statistics, probability, finance, verification, repeated calculations, or consequential results.
  • Ask for a missing assumption when it changes the problem; a call must not hide ambiguity.
  • The four tools are registered. Never call list_mcp_resources, inspect source, or use a shell to find them. Use math.run for a known operation; otherwise search, then describe only if needed.
  • For an obligation DAG, failures-only checkpoint, or receipt replay, do not search the MCP catalog. When this installed Skill contains the Host-generated scripts/math-anchor launcher, invoke it relative to this Skill directory with check-obligations or replay-obligations; retain receipts outside model context. Never substitute an ambient command or source checkout. If the launcher is absent, report that this carrier has no obligation checkpoint.
  • Every run uses the outer envelope {operation, arguments}. Put all operation-specific fields inside arguments; never flatten them beside operation.

Call these fully known routes directly; never search or describe these shapes first:

  • Fixed-width arithmetic: {"operation":"integer.machine_arithmetic","arguments":{"action":"add","left":"255","right":"2","bitWidth":8,"signedness":"unsigned","inputMode":"value","overflowBehavior":"wrapping"}}
  • Exact combinations/permutations: {"operation":"combinatorics.count","arguments":{"action":"binomial","n":52,"k":5}}
  • Checkable polynomial identity: {"operation":"certificate.polynomial_identity","arguments":{"left":"(x+1)^2","right":"x^2+2*x+1","variables":["x"]}}

Execute economically

  • Use one math.run, math.batch for 2–32 independent ordered calculations, or function.sample for one expression at many points. Batch is not a dependency graph.
  • For bulky output, select resultMode and raise maxOutputBytes only when useful.
  • Control digits with arguments.precision; precision is not a top-level math.run field. It counts significant digits. Exact fields stay exact. For decimal places, include integer digits plus at least two guard digits in the first call and round once for presentation.
  • Supply answer-changing variables, bounds, units, conventions, and tolerances.

Read the full file on GitHub · 86 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago Changed · -7 lines · -26 tokens per session 5ce24ddbcf25
  2. 10d ago First seen · 93 lines · 109 tokens per session scan A bbda7437b567

Subscribe to this mod's changes

calculate is a skill published in the GitHub repository tetracoralla/math-anchor (0 stars, last pushed 4d ago), licensed Apache-2.0. It adds 83 tokens to every session and 1,123 once invoked, about $0.0004 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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