model-usage

A command-line helper that summarizes local CodexBar cost logs by AI model, for Codex or Claude. It can show the latest model or a breakdown of all models.

In plain words
What is it for?
Use it to review recent model usage, compare models, or produce a scriptable JSON summary from a file, standard input, or CodexBar.
Why use it?
It removes the need to inspect raw cost data manually when you want to know which models were used and what they cost.

Skill for Claude CodeCodex

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/the-open-agent/openagent/model-usage
Any agent
npx skills add the-open-agent/openagent --skill model-usage
Clone the repo
git clone --depth 1 https://github.com/the-open-agent/openagent

Made for: Claude Code, Codex.

Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 562 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 $0.00069 $0.00562
Opus 5 $0.00034 $0.00281
Sonnet 5 $0.00014 $0.00112
Haiku 4.5 $0.00007 $0.00056

Measured 2d ago against content hash dbdd6e603d27, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

model-usage 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 2d 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.

Origin

Copies of this mod

8 near-identical copies found in the catalogue:

skills/model-usage/SKILL.md · 70 lines

What it actually says

Model usage

Overview

Get per-model usage cost from CodexBar's local cost logs. Supports "current model" (most recent daily entry) or "all models" summaries for Codex or Claude.

TODO: add Linux CLI support guidance once CodexBar CLI install path is documented for Linux.

Quick start

  1. Fetch cost JSON via CodexBar CLI or pass a JSON file.
  2. Use the bundled script to summarize by model.
python {baseDir}/scripts/model_usage.py --provider codex --mode current
python {baseDir}/scripts/model_usage.py --provider codex --mode all
python {baseDir}/scripts/model_usage.py --provider claude --mode all --format json --pretty

Current model logic

  • Uses the most recent daily row with modelBreakdowns.
  • Picks the model with the highest cost in that row.
  • Falls back to the last entry in modelsUsed when breakdowns are missing.
  • Override with --model <name> when you need a specific model.

Inputs

  • Default: runs codexbar cost --format json --provider <codex|claude>.
  • File or stdin:
codexbar cost --provider codex --format json > /tmp/cost.json
python {baseDir}/scripts/model_usage.py --input /tmp/cost.json --mode all
cat /tmp/cost.json | python {baseDir}/scripts/model_usage.py --input - --mode current

Output

  • Text (default) or JSON (--format json --pretty).
  • Values are cost-only per model; tokens are not split by model in CodexBar output.

References

  • Read references/codexbar-cli.md for CLI flags and cost JSON fields.
Files

What ships with it

1 file 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. 2d ago First seen · 70 lines · 69 tokens per session scan A dbdd6e603d27

Subscribe to this mod's changes

model-usage is a skill published in the GitHub repository the-open-agent/openagent (5,596 stars, last pushed today), licensed Apache-2.0. It adds 69 tokens to every session and 562 once invoked, about $0.0003 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 2026-08-30.