codex-usage-desktop: Instructions file for Codex

AGENTS.md

codex-usage-desktop AGENTS.md is an instructions file for Codex, OpenCode from itvincent-git/codex-usage-desktop. It costs 996 tokens per session, scanned A, original, MIT.

A set of instructions for coding agents that emphasizes thinking before coding, simple solutions, and narrowly scoped changes.

In plain words
What is it for?
Use it when planning an implementation, choosing between approaches, or modifying an existing codebase with minimal disruption.
Why use it?
It helps prevent unnecessary features, hidden assumptions, overcomplicated designs, and unrelated edits.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md; mentions Codex.

This is itvincent-git/codex-usage-desktop's own configuration. It tells Codex and OpenCode how to work on codex-usage-desktop 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 codex-usage-desktop configures →

Reuse

Borrowing it

Nothing to install: this file belongs to itvincent-git/codex-usage-desktop. 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/itvincent-git/codex-usage-desktop/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/itvincent-git/codex-usage-desktop

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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README.md
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<a href="https://agentmods.dev/instructions/itvincent-git/codex-usage-desktop/agents-md"><img src="https://agentmods.dev/badge/instructions/itvincent-git/codex-usage-desktop/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 996 This file is loaded in full into every session.
When invoked 996 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 $0.00996 $0.00996
Opus 5.5 $0.00398 $0.00398
Sonnet 5.5 $0.00199 $0.00199
Haiku 4.5 $0.00100 $0.00100

Measured 6d ago against content hash 6d9b0b88401f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

codex-usage-desktop 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 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.

AGENTS.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Behavioral guidelines to reduce common LLM coding mistakes. Merge with project-specific instructions as needed.

Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

  • State your assumptions explicitly. If uncertain, ask.
  • If multiple interpretations exist, present them - don't pick silently.
  • If a simpler approach exists, say so. Push back when warranted.
  • If something is unclear, stop. Name what's confusing. Ask.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

  • No features beyond what was asked.
  • No abstractions for single-use code.
  • No "flexibility" or "configurability" that wasn't requested.
  • No error handling for impossible scenarios.
  • If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

When editing existing code:

  • Don't "improve" adjacent code, comments, or formatting.
  • Don't refactor things that aren't broken.
  • Match existing style, even if you'd do it differently.
  • If you notice unrelated dead code, mention it - don't delete it.

When your changes create orphans:

  • Remove imports/variables/functions that YOUR changes made unused.
  • Don't remove pre-existing dead code unless asked.

The test: Every changed line should trace directly to the user's request.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Transform tasks into verifiable goals:

  • "Add validation" → "Write tests for invalid inputs, then make them pass"
  • "Fix the bug" → "Write a test that reproduces it, then make it pass"
  • "Refactor X" → "Ensure tests pass before and after"

For multi-step tasks, state a brief plan:

1. [Step] → verify: [check]
2. [Step] → verify: [check]
3. [Step] → verify: [check]

Read the full file on GitHub · 92 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.

  1. 6d ago Changed · -7 tokens per session 6d9b0b88401f
  2. 10d ago Changed · +1 lines · +21 tokens per session ac96ec683d9d
  3. 17d ago Changed · +16 tokens per session df1e4b09faab
  4. 1mo ago Changed · -8 lines · -122 tokens per session e16e926725af
  5. 2mo ago First seen · 99 lines · 1,088 tokens per session scan A 206e505a1ced

Subscribe to this mod's changes

codex-usage-desktop AGENTS.md is an instructions file published in the GitHub repository itvincent-git/codex-usage-desktop (60 stars, last pushed yesterday), licensed MIT. It adds 996 tokens to every session, about $0.0040 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.

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