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 tomzx/agents --skill create-assumptiongit clone --depth 1 https://github.com/tomzx/agentsWrote 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/tomzx/agents/create-assumption)<a href="https://agentmods.dev/skills/tomzx/agents/create-assumption"><img src="https://agentmods.dev/badge/skills/tomzx/agents/create-assumption/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/tomzx/agents/create-assumption"><img src="https://agentmods.dev/badge/skills/tomzx/agents/create-assumption.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 | $0.00020 | $0.00754 |
| Opus 5.5 | $0.00008 | $0.00302 |
| Sonnet 5.5 | $0.00004 | $0.00151 |
| Haiku 4.5 | $0.00002 | $0.00075 |
Grade A, and why
create-assumption 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 22d 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 — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Create Assumption
Records an assumption made during implementation: what is being assumed, why, how confident the team is, what breaks if the assumption is wrong, and how to validate it.
Assumptions differ from decisions: a decision is a deliberate choice between known options; an assumption is something believed to be true that has not been fully verified.
Prerequisites
- Apply the shared SDLC conventions in
skills/sdlc/references/shared.md. - An assumption that was made (implicitly or explicitly) during design or implementation
- Enough context to assess its basis and risk
Steps
- State the assumption clearly and specifically.
- Describe the basis: what evidence or reasoning supports it.
- Assess confidence level and risk if the assumption is wrong.
- Describe the impact on the implementation if the assumption turns out to be false.
- Define a validation plan: how and when to confirm or refute the assumption.
- Save the document to
.sdlc/knowledge/assumptions/using the filename patternN-<slug>.mdwhereNis the next available number (counting existing files in that directory).
Output Format
Use the template at skills/sdlc/templates/knowledge/assumption.md (copied to .sdlc/templates/knowledge/assumption.md by /initialize-sdlc-directory; use the project's customized copy if present).
Write the result to the artifact path named in the steps above.
Outcome
If $OUTCOME_YAML is set, emit verdict: approved there per skills/sdlc/references/shared.md once the record is written.
In the same emission, list the artifact under artifacts: (.sdlc/knowledge/assumptions/N-<slug>.md).
Example Usage
Scenario 1: Load assumption Assuming the service will handle at most 1,000 concurrent users based on the current contract. Basis: product manager's statement in the kick-off meeting. Confidence: Medium (verbal, not written). Risk if wrong: connection pool and caching strategy are sized for this load; exceeding it causes timeouts. Validation: confirm in writing with PM before go-live.
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.
- 22d ago Changed · -2 lines 9dba363cd94d
- 23d ago Changed · -4 lines 8c605a72f9e3
- 2mo ago First seen · 76 lines · 20 tokens per session scan A 5ab54461c83b
create-assumption is a skill published in the GitHub repository tomzx/agents (13 stars, last pushed yesterday), licensed MIT. It adds 20 tokens to every session and 754 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 2026-08-31.
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