fitness-functions

fitness-functions is a skill for Claude Code, Codex from fabiandistler/agents. It costs 45 tokens per session (2,045 once invoked), scanned A, original, no licence file.

A method for creating automated checks that enforce important properties of a software architecture, such as clear layers, low coupling, security, or resilience. These checks can run in continuous integration, the automated build and test process.

In plain words
What is it for?
Use it to define architecture rules, implement checks for them, and connect those checks to CI.
Why use it?
It helps detect architecture problems early instead of allowing the design to gradually deteriorate as code changes.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to define architecture rules, implement checks for them, and connect those checks to CI.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fabiandistler/agents/fitness-functions
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 fabiandistler/agents --skill fitness-functions
Clone the repo
git clone --depth 1 https://github.com/fabiandistler/agents

Made for: Claude Code, 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 fitness-functions

README.md
[![agentmods](https://agentmods.dev/badge/skills/fabiandistler/agents/fitness-functions/github.svg)](https://agentmods.dev/skills/fabiandistler/agents/fitness-functions)
Your own site
<a href="https://agentmods.dev/skills/fabiandistler/agents/fitness-functions"><img src="https://agentmods.dev/badge/skills/fabiandistler/agents/fitness-functions/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 fitness-functions

Your own site · 80×15
<a href="https://agentmods.dev/skills/fabiandistler/agents/fitness-functions"><img src="https://agentmods.dev/badge/skills/fabiandistler/agents/fitness-functions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,045 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 unknown 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 $0.00045 $0.02045
Opus 5.5 $0.00018 $0.00818
Sonnet 5.5 $0.00009 $0.00409
Haiku 4.5 $0.00005 $0.00204

Measured 4d ago against content hash 229d30f8a97c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fitness-functions 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 4d 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.

skills/fitness-functions/SKILL.md · 178 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

2 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. 4d ago Changed · +10 lines 229d30f8a97c
  2. 6d ago Changed · -14 lines · +8 tokens per session 7acfc87dbc7e
  3. 8d ago Changed · -1 lines · -9 tokens per session 99c6fc20dd25
  4. 10d ago Changed · +2 lines 28e60cc7d4b2
  5. 17d ago Changed · -2 lines b6d757822ffe
  6. 20d ago Changed · +1 lines 48bb8aeda2a7
  7. 1mo ago Changed · -6 lines 4bc09a05c326
  8. 1mo ago Changed · +5 lines a1f012788e7c
  9. 1mo ago Changed · +2 lines 600fef8d71a7
  10. 1mo ago First seen · 181 lines · 46 tokens per session scan A 142a893311dd

Subscribe to this mod's changes

fitness-functions is a skill published in the GitHub repository fabiandistler/agents (2 stars, last pushed yesterday), with no licence file. It adds 45 tokens to every session and 2,045 once invoked, about $0.0002 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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