cco-tools

cco-tools is a skill for Claude Code from egorfedorov/claude-context-optimizer. It costs 27 tokens per session (419 once invoked), scanned A, original, MIT.

A tool for measuring how many tokens different tools actually use, based on observed results. Tokens are units of text that affect an agent's context and usage budget.

In plain words
What is it for?
Use it to inspect average, worst-case, and total token usage by tool, then find expensive or unpredictable calls that may need narrower queries.
Why use it?
Fixed estimates can badly misrepresent the cost of tool calls, especially when one query returns much more data than another.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node src/tool-costs.js.

Part of the claude-context-optimizer plugin — 22 skills, 1 agent, 6 hooks shipped together

Good fit Use it to inspect average, worst-case, and total token usage by tool, then find expensive or unpredictable calls that may need narrower queries.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/egorfedorov/claude-context-optimizer
agentmods
npx agentmods add skills/egorfedorov/claude-context-optimizer/cco-tools

Made for: Claude Code.

Or install claude-context-optimizer, the plugin that ships this one along with the rest of its 22 skills, 1 agent, 6 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cco-tools

README.md
[![agentmods](https://agentmods.dev/badge/skills/egorfedorov/claude-context-optimizer/cco-tools.svg)](https://agentmods.dev/skills/egorfedorov/claude-context-optimizer/cco-tools)
Your own site
<a href="https://agentmods.dev/skills/egorfedorov/claude-context-optimizer/cco-tools"><img src="https://agentmods.dev/badge/skills/egorfedorov/claude-context-optimizer/cco-tools.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 419 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00027 $0.00419
Opus 5 $0.00014 $0.00210
Sonnet 5 $0.00005 $0.00084
Haiku 4.5 $0.00003 $0.00042

Measured 8d ago against content hash 7f1ef9fa7517, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

cco-tools 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 8d 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.

skills/cco-tools/SKILL.md · 51 lines

What it actually says

CCO Tools — what your tools really cost

MCP and Agent token costs used to be constants picked once (mcp__* ≈ 200 in, Agent ≈ 500). Real results vary by orders of magnitude — a "list all issues" query and a one-row lookup are the same tool name and nowhere near the same cost. On MCP-heavy sessions the budget meter was guessing at its biggest line item.

CCO now measures every tool result and learns the average per tool name.

Run from the plugin root:

show (or no arguments)

node src/tool-costs.js

Prints the learned table: calls, average, worst case, and cumulative total per tool, sorted by total spend.

When reading it back to the user, the useful observations are:

  • The top row by total is where their context budget actually goes. It is frequently an MCP server rather than file reads.
  • A row marked · has fewer than 3 samples and is still using the built-in constant — its estimate isn't trustworthy yet.
  • A large gap between avg and max means that tool is unpredictable; suggest narrowing its queries (filters, limits, pagination) rather than dropping it.

Pair with /cco-overhead mcp — that shows which servers are configured but never called; this shows what the called ones actually cost.

reset

node src/tool-costs.js reset

Clears the learned table and returns every tool to its built-in constant. Useful after changing MCP servers or their configuration, when past measurements no longer describe the current setup. Confirm before running — the history isn't recoverable.

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. 8d ago First seen · 51 lines · 27 tokens per session scan A 7f1ef9fa7517

Subscribe to this mod's changes

cco-tools is a skill published in the GitHub repository egorfedorov/claude-context-optimizer (107 stars, last pushed 6d ago), licensed MIT. It adds 27 tokens to every session and 419 once invoked, about $0.0001 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.

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