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 adamlinscott/claude-skills --skill assumption-inventorygit clone --depth 1 https://github.com/adamlinscott/claude-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/adamlinscott/claude-skills/assumption-inventory)<a href="https://agentmods.dev/skills/adamlinscott/claude-skills/assumption-inventory"><img src="https://agentmods.dev/badge/skills/adamlinscott/claude-skills/assumption-inventory/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/adamlinscott/claude-skills/assumption-inventory"><img src="https://agentmods.dev/badge/skills/adamlinscott/claude-skills/assumption-inventory.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00152 | $0.01544 |
| Opus 5 | $0.00076 | $0.00772 |
| Sonnet 5 | $0.00030 | $0.00309 |
| Haiku 4.5 | $0.00015 | $0.00154 |
Grade A, and why
assumption-inventory 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 10d 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 — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Assumption Inventory
Before a long run, the cheapest bug to fix is a wrong premise. This skill is a preflight: surface the assumptions the next stretch of work rests on, separate what you can cite from what you are guessing, and confirm the load-bearing guesses before the work starts — not after the diff lands.
The mechanism is one distinction held strictly: a fact is something on disk or stated by the user (it gets a citation); an assumption is everything else (it does not). The danger is an uncited assumption quietly becoming load-bearing — the work builds on it, and the divergence only surfaces hours later. This skill drags those assumptions into the open and gates the load-bearing ones on evidence or confirmation.
This is the front end of the triad: assumption-inventory (before), reground
(mid-drift), fresh-eyes (after). Run it in order; do not skip to step 4.
1. Decide whether to run
Run this when the work ahead is long, expensive, hard to reverse, or multi-step and the target is not already crisply pinned. Skip it for a one-line change with an explicit target — the ceremony is not free. When in doubt on a big task, run it.
2. Draft the inventory
Fill every slot. For each, tag the basis: [cited: file:line / user said X] for a fact,
[assumption] for a guess. Do not leave a slot blank — "unknown" is a valid, important
answer.
- Goal — what outcome am I trying to produce, in one sentence? Why now?
- Root / scope — which repo, directory, or workspace is this rooted in? Is it workspace-wide or one repo? What platform(s) must it run on?
- May edit — which files / areas am I allowed to change?
- Must not touch — what is off-limits (generated files, other repos, prod config, contracts other code depends on)?
- Done means — what concrete, checkable state counts as complete? How will I know?
- Open questions — what do I not know yet that could change the above?
3. Stress the assumptions
For each [assumption], ask: what is the cheapest evidence that would settle this, and
have I looked? Then look. Read the file, run pwd / git remote -v, check for a
CLAUDE.md or ADR, grep for the symbol. Cheap checks turn guesses into citations now,
before they cost anything. See REFERENCE.md for the catalog of
assumptions that are silently wrong most often (platform, scope, auth, volatile
contracts) — check those by default even when they feel obvious.
What ships with it
1 file 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.
- 10d ago First seen · 105 lines · 152 tokens per session scan A e4d4523dd44e
assumption-inventory is a skill published in the GitHub repository adamlinscott/claude-skills (3 stars, last pushed 10d ago), licensed MIT. It adds 152 tokens to every session and 1,544 once invoked, about $0.0008 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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