tokf-discover

tokf-discover is a skill for Claude Code from mpecan/tokf. It costs 20 tokens per session (559 once invoked), scanned A, original, MIT.

A session-analysis tool that scans Claude Code command history to find shell commands producing more text than needed and suggests matching filters.

In plain words
What is it for?
Use it to scan recent or selected Claude Code sessions, compare commands with available filters, and export the findings as JSON.
Why use it?
It helps identify repeated verbose output that consumes extra AI context and tokens. It also shows where filtering could reduce that waste.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions Claude Code.

Good fit Use it to scan recent or selected Claude Code sessions, compare commands with available filters, and export the findings as JSON.

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Install with agentmods
npx agentmods add skills/mpecan/tokf/tokf-discover
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.

Any agent
npx skills add mpecan/tokf --skill tokf-discover
Clone the repo
git clone --depth 1 https://github.com/mpecan/tokf

Made for: Claude Code.

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 tokf-discover

README.md
[![agentmods](https://agentmods.dev/badge/skills/mpecan/tokf/tokf-discover/github.svg)](https://agentmods.dev/skills/mpecan/tokf/tokf-discover)
Your own site
<a href="https://agentmods.dev/skills/mpecan/tokf/tokf-discover"><img src="https://agentmods.dev/badge/skills/mpecan/tokf/tokf-discover/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for tokf-discover

Your own site · 80×15
<a href="https://agentmods.dev/skills/mpecan/tokf/tokf-discover"><img src="https://agentmods.dev/badge/skills/mpecan/tokf/tokf-discover.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 559 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 $0.00020 $0.00559
Opus 5 $0.00010 $0.00280
Sonnet 5 $0.00004 $0.00112
Haiku 4.5 $0.00002 $0.00056

Measured 9d ago against content hash 3a195529f0c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

tokf-discover 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 9d 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.

crates/tokf-cli/skills/tokf-discover/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

tokf discover — Find Missed Token Savings

Use this skill to analyze Claude Code sessions and find commands that are running without tokf filtering, wasting tokens on verbose output.

Quick Start

Run tokf discover in the project directory to scan recent sessions:

tokf discover

Options

  • --all — scan all projects, not just the current one
  • --since 7d — only scan sessions from the last 7 days (also 24h, 30m)
  • --limit 0 — show all results (default: top 20)
  • --json — output as JSON for programmatic use
  • --session <path> — scan a specific session file
  • --project <path> — scan sessions for a specific project path

Interpreting Results

The output shows:

  • COMMAND — the shell command pattern being run without filtering
  • FILTER — the tokf filter that would handle it
  • RUNS — how many times it appeared in sessions
  • TOKENS — estimated token count of unfiltered output
  • SAVINGS — estimated tokens that filtering would save

Workflow

  1. Run tokf discover to identify top savings opportunities
  2. For commands with existing filters: run tokf hook install to set up automatic filtering
  3. For commands without filters: use /tokf-filter skill to create a custom filter
  4. Re-run tokf discover after changes to verify improvement

Creating Filters for Unfiltered Commands

If tokf discover shows commands with no matching filter, create one:

# See what a filter would look like
tokf which "the-command --args"

# Use the tokf-filter skill to create a proper filter
# /tokf-filter

JSON Output

Use --json for integration with other tools:

tokf discover --json | jq '.results[] | select(.estimated_savings > 1000)'

The JSON schema includes:

  • sessions_scanned — number of JSONL files processed
  • total_commands — all Bash commands found
  • already_filtered — commands already using tokf
  • filterable_commands — commands with available filters
  • no_filter_commands — commands with no matching filter
  • estimated_total_savings — total estimated token savings
  • results[] — per-command breakdown sorted by savings

Read the full file on GitHub · 72 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. 9d ago First seen · 72 lines · 20 tokens per session scan A 3a195529f0c0

Subscribe to this mod's changes

tokf-discover is a skill published in the GitHub repository mpecan/tokf (197 stars, last pushed yesterday), licensed MIT. It adds 20 tokens to every session and 559 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.