How do I install the Model Usage skill?

Run npx skillmds@latest add understudy-ai/model-usage in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Model Usage safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Model Usage?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Model Usage free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Model Usage?

understudy-ai (@understudy-ai) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Model Usage by understudy-ai — Agent Skill

Name: Model Usage
Author: understudy-ai

Model Usage

Use CodexBar CLI local cost usage to summarize per-model usage for Codex or Claude, including the current (most recent) model or a full model breakdown. Trigger when asked for model-level usage/cost data from codexbar, or when you need a scriptable per-model summary from codexbar cost JSON.

understudy-ai Updated Sep 21, 2026

File contents

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

Fetch cost JSON via CodexBar CLI or pass a JSON file.
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.

Frequently asked questions