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.
npx skills add cyfung1031/skills --skill context-compressorgit clone --depth 1 https://github.com/cyfung1031/skillsWrote 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.
[](https://agentmods.dev/skills/cyfung1031/skills/context-compressor)<a href="https://agentmods.dev/skills/cyfung1031/skills/context-compressor"><img src="https://agentmods.dev/badge/skills/cyfung1031/skills/context-compressor.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00045 | $0.00878 |
| Opus 5 | $0.00023 | $0.00439 |
| Sonnet 5 | $0.00009 | $0.00176 |
| Haiku 4.5 | $0.00005 | $0.00088 |
Grade A, and why
context-compressor 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Compressor
Core invariant: preserve what changes future work; compress everything else.
Activate / stop
Use when the user requests low-token, terse, brief, compressed, continuation, handoff, or task-critical-state preservation; when a system/tool signal indicates compaction, truncation, limited context, or token pressure; or when state-loss risk is visible: long thread, large pasted content, repeated tool output, multiple changed files, accepted decisions, non-obvious findings, or unresolved validation.
Do not use for ordinary article summaries, one-off shortening, or code review unless the user also wants compact mode or continuation state. Explicit compact mode persists until the user asks for normal/detail or the task ends. Proactive use is temporary for the current phase or handoff.
Priority ladder
- Safety, privacy, permissions, policy.
- Required tool/artifact workflow, validation, citations, fixed formats, and exact user constraints.
- Latest user request for detail, code, examples, language, tone, or format.
- Compression.
When another skill applies, run that skill's required workflow and compress only narration, repeated setup, logs, and nonessential explanation.
Operating rules
- Answer the latest request first; put requested code, decision, artifact, or summary before background.
- Use the smallest sufficient form: micro update, concise answer, dense-source note, or full handoff.
- In long work, mention only new action, finding, verification, blocker, changed next step, or material risk.
- Prefer exact identifiers: paths, symbols, branches, issue numbers, dates, commands, tests, source names, line ranges.
- Ask at most one clarifying question only when blocked; otherwise state a safe behavior-affecting assumption and proceed.
- Preserve requested language, tone, register, domain terms, grammar quirks, and localization constraints when material.
- Never translate, normalize, paraphrase, reorder, or repair protected literals unless asked: code, commands, logs, errors, regexes, schemas, API signatures, config keys, URLs, paths, prompts, placeholders, names, quotes, multilingual text, and fixed-format fields.
- Do not claim exact token savings, remaining context window, truncation risk, coverage, validation, or completion without visible telemetry or evidence.
What ships with it
11 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 6d ago First seen · 69 lines · 45 tokens per session scan A a3057c649cac
context-compressor is a skill published in the GitHub repository cyfung1031/skills (2 stars, last pushed 26d ago), licensed MIT. It adds 45 tokens to every session and 878 once invoked, about $0.0002 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 2026-08-31.
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