skillsbench: Instructions file for Codex

AGENTS.md

skillsbench AGENTS.md is an instructions file for Codex, OpenCode from benchflow-ai/skillsbench. It costs 692 tokens per session, scanned A, original, Apache-2.0.

A set of instructions for SkillsBench, a benchmark that measures how well AI coding agents use skills to complete tasks. It includes task layouts, commands, and evaluation rules.

In plain words
What is it for?
Use it to initialize benchmark tasks, validate task files, run agents with or without skills, and evaluate a skill against its test cases.
Why use it?
It gives agents and developers a shared way to create, check, and compare skill-based tasks. This reduces confusion about how benchmarks should be structured and run.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: reads .claude/ paths.

This is benchflow-ai/skillsbench's own configuration. It tells Codex and OpenCode how to work on skillsbench 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 skillsbench configures →

About the project

SkillsBench is a benchmark for measuring how effectively AI agents use modular skills—folders containing instructions, scripts, and resources—to complete specialized tasks. It helps researchers and developers evaluate both skill quality and agent behavior, including tasks that require combining multiple skills. The catalogue’s skills and instructions are evaluated as part of this workflow.

benchflow-ai/skillsbench · 1,867 stars · on GitHub · skillsbench.ai

Reuse

Borrowing it

Nothing to install: this file belongs to benchflow-ai/skillsbench. 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/benchflow-ai/skillsbench/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/benchflow-ai/skillsbench

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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README.md
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Per session 692 This file is loaded in full into every session.
When invoked 692 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 $0.00692 $0.00692
Opus 5.5 $0.00277 $0.00277
Sonnet 5.5 $0.00138 $0.00138
Haiku 4.5 $0.00069 $0.00069

Measured 1mo ago against content hash 11d227e867ba, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

skillsbench 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 · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SkillsBench

Benchmark for evaluating how well AI agents use skills. 87 default runnable task definitions, expanding toward 100+.

Commands

uv tool install "benchflow>=0.6.2,<0.7"
uv sync --locked
bench tasks init <task-id>
bench tasks check tasks/<task-id>
bench eval run --tasks-dir tasks/<task-id> --agent oracle --sandbox docker
bench eval run --tasks-dir tasks/<task-id> --agent claude-agent-acp --model <model> --skill-mode with-skill --skills-dir tasks/<task-id>/environment/skills/
bench eval run --tasks-dir tasks/<task-id> --agent claude-agent-acp --model <model> --skill-mode no-skill
bench skills list
bench skills eval <skill-dir>   # evaluate a skill against its evals/evals.json

Task Layout

SkillsBench tasks are native BenchFlow task.md packages:

tasks/<task-id>/
  task.md                 # YAML frontmatter + human-written prompt body
  environment/
    Dockerfile            # Container setup
    skills/               # Domain skills (generalizable, not task-specific)
  oracle/
    solve.sh              # Oracle (human-written, derives answers via computation)
  verifier/
    test.sh               # Pytest runner, writes reward.txt
    test_outputs.py       # Outcome-based assertions

Default runnable tasks live in tasks/. Credential-dependent or integration-incompatible tasks live in tasks-extra/ and are included in integration sweeps only when --no-default-excludes is passed.

Rules

  • task.md prompt body and oracle/solve.sh must be human-written — never generate these
  • Never mention skill names in the task prompt
  • Skills must be generalizable and reusable, not task-specific
  • Tests verify outcomes, not process — don't check which tools were used
  • Oracle must derive answers through computation, not hardcode them
  • No fake scenarios, no synthetic data when real data exists
  • Prefer tasks without external API dependencies
  • task.md frontmatter metadata must validate against taxonomy.yaml — pick category from the controlled list, plus subcategory, task_type, modality, interface, skill_type. See taxonomy.md for the codebook and decision rules. CI runs .github/scripts/lint_taxonomy.py on every PR that touches tasks/**/task.md.

Read the full file on GitHub · 59 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. 1mo ago First seen · 59 lines · 692 tokens per session scan A 11d227e867ba

Subscribe to this mod's changes

skillsbench AGENTS.md is an instructions file published in the GitHub repository benchflow-ai/skillsbench (1,867 stars, last pushed today), licensed Apache-2.0. It adds 692 tokens to every session, about $0.0028 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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