usage-kernel

usage-kernel is a skill for Claude Code, Codex from douglasmonsky/codex-usage-tracker. It costs 28 tokens per session (1,030 once invoked), scanned A, original, MIT.

A set of six tools for checking exact local Codex usage data. It supports defined usage queries, limited exploration, allowance observations, and timelines of supporting evidence.

In plain words
What is it for?
Use it to query usage totals, inspect allowances and tracker status when needed, explore bounded usage data, and build evidence timelines.
Why use it?
It helps answer usage questions from local tracker data instead of relying on guesses. It also reports how current and reliable the available data is.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex.

Good fit Use it to query usage totals, inspect allowances and tracker status when needed, explore bounded usage data, and build evidence timelines.

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Install with agentmods
npx agentmods add skills/douglasmonsky/codex-usage-tracker/usage-kernel
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 douglasmonsky/codex-usage-tracker --skill usage-kernel
Clone the repo
git clone --depth 1 https://github.com/douglasmonsky/codex-usage-tracker

Made for: Claude Code, Codex.

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 usage-kernel

README.md
[![agentmods](https://agentmods.dev/badge/skills/douglasmonsky/codex-usage-tracker/usage-kernel/github.svg)](https://agentmods.dev/skills/douglasmonsky/codex-usage-tracker/usage-kernel)
Your own site
<a href="https://agentmods.dev/skills/douglasmonsky/codex-usage-tracker/usage-kernel"><img src="https://agentmods.dev/badge/skills/douglasmonsky/codex-usage-tracker/usage-kernel/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 usage-kernel

Your own site · 80×15
<a href="https://agentmods.dev/skills/douglasmonsky/codex-usage-tracker/usage-kernel"><img src="https://agentmods.dev/badge/skills/douglasmonsky/codex-usage-tracker/usage-kernel.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,030 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high System Prompt Leakage · line 80
    Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.
    Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
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 $0.00028 $0.01030
Opus 5.5 $0.00011 $0.00412
Sonnet 5.5 $0.00006 $0.00206
Haiku 4.5 $0.00003 $0.00103

Measured 1mo ago against content hash 39e746389bb0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

usage-kernel 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 1mo 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/usage-kernel/SKILL.md · 82 lines

How it starts

The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codex Usage Tracker

Use the tracker as a factual local data plane. The tools return exact or explicitly graded facts; the model owns inference, explanation, and recommendations.

Use the three-step loop scope → batch → evidence:

  1. Scope. Start with the needed usage_query whenever the question maps to a curated template or a known typed request. The result carries its generation, grade, history coverage, and cache state. Call usage_status only when the query reports an absent or insufficiently fresh index, or when the user explicitly asks about operational state. A committed generation remains queryable while refresh is active or recommended. When the needed fields are unfamiliar, set include_guidance=true on the same usage_query call that carries the first batch; use an empty batch only for standalone capability discovery.
  2. Batch. Prefer one batched usage_query call. Its arguments always wrap one or more query requests in the requests array. Execute a curated server-side template with {"requests":[{"template":"<name>"}]}; for the common thread leaderboard use {"requests":[{"template":"top_threads"}]}. Templates query the hydrated snapshot and report its coverage; refresh complete history only when the user asks. For same five ranked threads, use result 1 for labels, selectors, totals, shares, and token classes; use result 2 only for cost/credits. Do not query again unless user asks for evidence. Use {"requests":[{"template":"weekly_drivers"}]} for the latest indexed seven-day thread leaderboard, {"requests":[{"template":"week_over_week"}]} for that window versus the immediately preceding seven days, and {"requests":[{"template":"latest_incremental_change"}]} for the active generation's inserted calls and leading affected thread. These templates derive their anchors from the committed snapshot; do not discover dates or generation numbers first. Use {"requests":[{"template":"model_effort"}]} for model/effort mix and {"requests":[{"template":"tools"}]} for structural tool facts. Do not repeat a successful curated template or request guidance after it returns rows. Supply parameters only when the selected template requires them. Otherwise send only the typed dataset, operation, dimensions, measures, filters, and limits needed for the question. Do not copy or reconstruct a returned template body. Preserve the returned generation, grade, coverage, counts, and explicit row/byte limits. Compose filters as {field, operator, value} using only the dataset fields and operators in filter_grammar; in takes an array of 1–25 values. Phase queries require one returned scope-filter template for a thread, turn, or time window.
  3. Evidence. Rank candidates from the facts first. Call usage_evidence only after ranking, and only with an exact returned logical selector. Use live=true for the same timeline in live mode.

Label every claim:

  • fact — returned exact/deterministic data; for partial, state the hydration preset/cutoff and never generalize to all history;
  • estimate — returned estimated data with coverage and provenance;
  • hypothesis — model inference that still needs evidence;
  • unsupported — unavailable from the returned scope and not asserted.

The optional context dataset is aggregate-only private local evidence. Its observed_bytes and events measures are exact for the structurally observed payload strings that were indexed. estimated_tokens is available only when an explicit tokenizer populated it; always preserve its estimator identity and coverage. Never describe category bytes or estimates as exact billed input tokens, and keep unattributed_input_tokens unsupported when the response reports it as null. If context composition is disabled, continue with the base accounting datasets instead of starting hidden work.

Call usage_refresh only when freshness matters. Reuse the returned job; never start a duplicate. Use usage_job_status with a bounded wait_seconds value so the host waits; do not short-interval poll from the model. Use usage_allowance for observed allowance facts and preserve its provenance and limitations. Do not infer waste or productivity from token totals alone.

Read the full file on GitHub · 82 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. 1mo ago First seen · 82 lines · 28 tokens per session scan A 39e746389bb0

Subscribe to this mod's changes

usage-kernel is a skill published in the GitHub repository douglasmonsky/codex-usage-tracker (196 stars, last pushed yesterday), licensed MIT. It adds 28 tokens to every session and 1,030 once invoked, about $0.0001 per session on Opus 5.5. 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.