mental-model

mental-model is a skill for Claude Code, Codex from automazeio/mental-model-skill. It costs 31 tokens per session (254 once invoked), scanned A, original, Apache-2.0.

A living document that records how a codebase is structured, how its parts interact, and how it is tested.

In plain words
What is it for?
Use it when exploring an unfamiliar project, debugging unexpected behavior, or maintaining shared notes about architecture, data flow, setup, and tests.
Why use it?
It gives the coding agent background before making changes and is updated when new behavior or patterns are discovered. If it does not exist, the agent asks before creating one.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

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.

agentmods
npx agentmods add skills/automazeio/mental-model-skill/mental-model
Any agent
npx skills add automazeio/mental-model-skill --skill mental-model
Clone the repo
git clone --depth 1 https://github.com/automazeio/mental-model-skill

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 mental-model

README.md
[![agentmods](https://agentmods.dev/badge/skills/automazeio/mental-model-skill/mental-model.svg)](https://agentmods.dev/skills/automazeio/mental-model-skill/mental-model)
Your own site
<a href="https://agentmods.dev/skills/automazeio/mental-model-skill/mental-model"><img src="https://agentmods.dev/badge/skills/automazeio/mental-model-skill/mental-model.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 254 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00031 $0.00254
Opus 5 $0.00015 $0.00127
Sonnet 5 $0.00006 $0.00051
Haiku 4.5 $0.00003 $0.00025

Measured 6d ago against content hash 9279b965ef8d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

mental-model 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.

mental-model/SKILL.md · 28 lines

What it actually says

Mental Model

When working on this codebase, first check for mental-model.md in the project root.

If it exists

Read it to understand the codebase architecture, patterns, conventions, and relationships before making changes, when exploring unfamiliar parts of the code, or debugging failed tests or unexpected behavior.

Update it whenever you discover something new — from running tests, hitting unexpected behavior, or exploring unfamiliar parts of the code.

If it doesn't exist

Ask the user if they'd like you to create one. If confirmed:

Create a new file named mental-model.md at the repo root, that builds and maintains a full mental model of the codebase.

Scan the entire codebase and document how the system works end-to-end (architecture, key modules, data flow, relationships, testing approach, Docker/setup, etc).

Treat this as a living document. Update it whenever you learn something new from running tests or hitting unexpected behavior.

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 First seen · 28 lines · 31 tokens per session scan A 9279b965ef8d

Subscribe to this mod's changes

mental-model is a skill published in the GitHub repository automazeio/mental-model-skill (5 stars, last pushed 7mo ago), licensed Apache-2.0. It adds 31 tokens to every session and 254 once invoked, about $0.0002 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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