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Agent skill

Cost Tracking

by affaan-m in affaan-m/ECC

Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log.

MITAuto-check passedAI & LLM Engineering

Install Cost Tracking

skills CLI
$ npx skills add affaan-m/ECC --skill cost-tracking -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install affaan-m/ECC cost-tracking --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/affaan-m/ECC.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/cost-tracking .claude/skills/cost-tracking && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
cost-tracking
GitHub stars
277k
Used in
1 other repo
Token cost
~1.3k tokens
SKILL.md length
464 words
Files
1
Skills in repo
683
Repo updated
First seen
Licence
MIT

At a glance

Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log.

  • The user asks about costs
  • SKILL.md covers Where the data lives, When to Use, How It Works and Example — summary, by model,…, plus 3 more sections
  • Calls node
  • Cost breakdowns by model

What it does

Cost Tracking is an agent skill from affaan-m/ECC. Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log. Use when the user asks about costs, spending, usage, tokens, budgets, or cost breakdowns by model, session, or date.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in AI & LLM Engineering, covering LLM cost and token optimization. The repository describes itself as: The agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Codex, Opencode, Cursor and beyond. The licence is MIT.

When your agent uses it

  • The user asks about costs
  • Cost breakdowns by model

Example prompts

  • “/cost-tracking”

What it can do on your machine

Read from SKILL.md and the folder at commit 2d515e4. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • node

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Cost Tracking loads about 1.3k tokens when it runs. Until then it costs about 60 tokens; SKILL.md has 464 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~60
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from affaan-m/ECC at commit 2d515e4, republished under its MIT licence (© affaan-m). 464 words, ~1,273 tokens.

Download SKILL.mdSave it as .claude/skills/cost-tracking/SKILL.md (or your agent's skills folder).
name
cost-tracking
description
Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log. Use when the user asks about costs, spending, usage, tokens, budgets, or cost breakdowns by model, session, or date.
metadata.origin
community

Cost Tracking

Use this skill to analyze Claude Code cost and usage history from the metrics log that ECC's stop:cost-tracker hook writes.

Where the data lives

The tracker appends one JSON object per session-stop to ~/.claude/metrics/costs.jsonl. Each row is a cumulative snapshot for that session, so to total spend you take the latest row per session_id and sum across sessions — summing every row multiply-counts.

ECC also maintains internal per-session files under ~/.claude/metrics/cost-snapshots/ so runtime hooks can read the current session total without rescanning all history. Treat those files as a rebuildable cache; each snapshot stores a byte cursor so only newly appended rows are scanned. Stable reads are O(1), while updates are O(new bytes). Stale entries are pruned after 30 days or when the directory exceeds 512 sessions. Cold catch-up work is limited to 16 MiB per hook invocation, and malformed unterminated rows larger than 1 MiB are discarded with a resumable cursor. Reports and exports should continue to use costs.jsonl.

Row schema:

FieldMeaning
timestampISO timestamp of the snapshot
session_idClaude Code session identifier
transcript_pathPath to the session transcript
modelModel used
input_tokens / output_tokensToken counts
cache_write_tokens / cache_read_tokensPrompt-cache token counts
estimated_cost_usdPrecomputed cumulative cost in USD for the session

Prefer estimated_cost_usd over hand-calculating pricing — model and cache prices change, and the tracker is the source of truth.

When to Use

  • The user asks "how much have I spent?", "what did this session cost?", or "what is my token usage?"
  • The user mentions budgets, spending limits, overruns, or cost controls.
  • The user wants a cost breakdown by model, session, or date, or a CSV export.
Show full SKILL.md (196 more words)Show less

How It Works

First verify the log exists (use node, not sqlite3 — the tracker writes JSONL, and node is cross-platform):

bash
node -e 'const fs=require("fs"),os=require("os"),p=require("path");const f=p.join(os.homedir(),".claude","metrics","costs.jsonl");console.log(fs.existsSync(f)?"cost log found":"cost log not found: "+f)'

If the log is missing, do not fabricate usage data. Tell the user that cost tracking populates after the first session ends with the stop:cost-tracker hook enabled.

Example — summary, by model, last 7 days

bash
node -e '
const fs=require("fs"),os=require("os"),path=require("path");
const f=path.join(os.homedir(),".claude","metrics","costs.jsonl");
if(!fs.existsSync(f)){console.log("cost log not found: "+f);process.exit(0);}
const rows=fs.readFileSync(f,"utf8").split(/\r?\n/).filter(Boolean).map(l=>{try{return JSON.parse(l)}catch{return null}}).filter(Boolean);
const bySession=new Map();
for(const r of rows){const k=r.session_id||r.transcript_path||r.timestamp;const p=bySession.get(k);if(!p||String(r.timestamp)>String(p.timestamp))bySession.set(k,r);}
const latest=[...bySession.values()];
const cost=r=>Number(r.estimated_cost_usd)||0, day=r=>String(r.timestamp||"").slice(0,10), sum=a=>a.reduce((s,r)=>s+cost(r),0), f4=n=>"$"+n.toFixed(4);
const today=new Date().toISOString().slice(0,10), yest=new Date(Date.now()-864e5).toISOString().slice(0,10);
console.log("today: "+f4(sum(latest.filter(r=>day(r)===today)))+" | yesterday: "+f4(sum(latest.filter(r=>day(r)===yest)))+" | total: "+f4(sum(latest))+" ("+latest.length+" sessions)");
const m=new Map();for(const r of latest){const k=r.model||"(unknown)";m.set(k,(m.get(k)||0)+cost(r));}
console.log("by model:");[...m.entries()].sort((a,b)=>b[1]-a[1]).forEach(([k,v])=>console.log("  "+f4(v)+"  "+k));
'

For a session drilldown or CSV export, iterate the same latest set (or the raw rows for CSV) and print the fields you need.

Reporting Guidance

When presenting cost data, include today's spend vs yesterday, total across all sessions, a by-model breakdown, and session count. Format sub-dollar amounts with four decimals, larger amounts with two.

Anti-Patterns

  • Do not sum every row — they are cumulative per session; reduce to the latest row per session_id first.
  • Do not estimate costs from raw token counts when estimated_cost_usd is present.
  • Do not assume the log exists without checking.
  • Do not hard-code current model pricing in user-facing answers.
  • Do not recommend installing unreviewed hooks or plugins that execute arbitrary code.
  • /cost-report - Command-form report over the same metrics log.
  • cost-aware-llm-pipeline - Model-routing and budget-design patterns.
  • token-budget-advisor - Context and token-budget planning.
  • strategic-compact - Context compaction to reduce repeated token spend.

© affaan-m, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/cost-tracking of affaan-m/ECC.

Open the folder on GitHubat commit 2d515e4

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in affaan-m/ECC, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Cost Tracking next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Cost Tracking compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Cost Tracking this skillaffaan-m/ECC277k1 repos~1.3kAutomated safety check: PassMIT
Context Compressionguanyang/open-agent-hub9772 repos~4.6kAutomated safety check: PassMIT
Bounty Hunter1sadjlk/bounty-hunter-skill2821 repos~761Automated safety check: PassMIT
Skill Shortenerluongnv89/asm955—~3.8kAutomated safety check: NotesMIT
Context Auditundefined-ui/second-brain-os1k—~802Automated safety check: PassMIT
Headroommomori777/Artemis380—~562Automated safety check: PassMIT

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Categories

Questions about Cost Tracking

What does Cost Tracking do?

Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log. Cost Tracking is an agent skill from affaan-m/ECC. Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log.

When should I use Cost Tracking?

Cost Tracking fits situations like: the user asks about costs; cost breakdowns by model.

How do I install Cost Tracking in Claude Code?

Run `npx skills add affaan-m/ECC --skill cost-tracking -a claude-code`. Or copy the skill folder (skills/cost-tracking in affaan-m/ECC) into .claude/skills/cost-tracking in your project. Claude Code loads it when a task matches its description.

How do I install Cost Tracking in Codex?

Run `npx skills add affaan-m/ECC --skill cost-tracking -a codex`. Or copy the skill folder (skills/cost-tracking in affaan-m/ECC) into .agents/skills/cost-tracking in your project. Codex loads it when a task matches its description.

Can I use Cost Tracking in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add affaan-m/ECC --skill cost-tracking -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/cost-tracking, .gemini/skills/cost-tracking, .github/skills/cost-tracking and .opencode/skills/cost-tracking in your project.

What does Cost Tracking need to run?

Going by SKILL.md and its folder, Cost Tracking needs the command-line tools its instructions call (node).

Does Cost Tracking access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Cost Tracking safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Cost Tracking use?

Cost Tracking is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Cost Tracking use?

About 1.3k tokens (SKILL.md is roughly 5.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Cost Tracking?

Skills that share tags, products or a category with Cost Tracking: Context Compression (guanyang/open-agent-hub, 977 stars), Bounty Hunter (1sadjlk/bounty-hunter-skill, 282 stars), Skill Shortener (luongnv89/asm, 955 stars) and Context Audit (undefined-ui/second-brain-os, 1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Cost Tracking?

affaan-m (a GitHub user) maintains it in affaan-m/ECC, which has 276,673 GitHub stars. The repository holds 683 skills in this directory. The repository was last updated on October 11, 2026.

Source: affaan-m/ECC on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.