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 IgorGanapolsky/ThumbGate --skill context-engineering-checklistgit clone --depth 1 https://github.com/IgorGanapolsky/ThumbGateWrote 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/igorganapolsky/thumbgate/context-engineering-checklist)<a href="https://agentmods.dev/skills/igorganapolsky/thumbgate/context-engineering-checklist"><img src="https://agentmods.dev/badge/skills/igorganapolsky/thumbgate/context-engineering-checklist/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.
<a href="https://agentmods.dev/skills/igorganapolsky/thumbgate/context-engineering-checklist"><img src="https://agentmods.dev/badge/skills/igorganapolsky/thumbgate/context-engineering-checklist.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00099 | $0.00745 |
| Opus 5 | $0.00049 | $0.00373 |
| Sonnet 5 | $0.00020 | $0.00149 |
| Haiku 4.5 | $0.00010 | $0.00075 |
Grade A, and why
context-engineering-checklist 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.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Engineering Checklist (HF course → ThumbGate)
Source: The Context Course
Pick the right layer (Clarify)
| Need | Layer | Do not |
|---|---|---|
| How-to / policy for agents | Skill (Unit 1) | Long chat-only prompts |
| External API/tool | MCP (Unit 2) | Fake tools in prose |
| Multi-step pack / fan-out | Workflow/plugin (Unit 3) | One mega-prompt |
| Parallel specialists | Sub-agents (Unit 4) | Dual-edit without locks |
| Irreversible deny | Hook/gate (Unit 5) | Skill-only “never do X” |
Unit 1 — Skills
-
SKILL.mdfrontmatter:name, trigger-richdescription, slash - One failure class per skill
- NEVER / ALWAYS table with zero-ratio rules
- Scripts for mechanical steps; no secrets in body
Unit 2 — MCP
- Tool names match discovery / allowlist
- Side-effect annotations truthful
- Mutating tools covered by PreToolUse / gate-check
Unit 3 — Plugins / workflows
- Context → specialists → verify → synthesize
- Smoke + full modes; read-only reviews
Unit 4 — Sub-agents
- Linear claim or complement (no steal)
- Vault one-writer; scoped prompts
Unit 5 — Hooks / gates
- Matchable tool surface (not English prose)
- Hard floor if irreversible
- Deny + allow + false-positive tests
- Live probe before “protected”
Six-block context envelope
Before generation, package reusable context into all six blocks:
goal: one measurable outcome.businessData: current evidence with source and timestamp.examples: concrete good or bad few-shot cases.procedures: ordered actions and verification.constraints: safety, business, and SLA limits.rubric: grading criteria supplied before the answer is generated.
Use construct_context_pack.contextEnvelope instead of repeating these blocks
in chat. All blocks are required when the envelope is present, count against
maxChars, and are part of semantic-cache identity.
What ships with it
2 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.
- 9d ago First seen · 86 lines · 99 tokens per session scan A a1488c79f33c
context-engineering-checklist is a skill published in the GitHub repository IgorGanapolsky/ThumbGate (26 stars, last pushed today), licensed MIT. It adds 99 tokens to every session and 745 once invoked, about $0.0005 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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