microsoft/wassette is a runtime that loads WebAssembly Components as tools exposed through the Model Context Protocol (MCP), an interface that lets AI agents use external capabilities. It is for extending coding agents with reusable tools while isolating those tools in a Wasmtime security sandbox. The catalogue skills, instructions, and agent help configure and operate Wassette with supported MCP clients.
Borrowing it
Nothing to install: this file belongs to microsoft/wassette. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/microsoft/wassette/main/.agents/skills/documentation/SKILL.mdgit clone --depth 1 https://github.com/microsoft/wassetteWrote 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/microsoft/wassette/documentation)<a href="https://agentmods.dev/skills/microsoft/wassette/documentation"><img src="https://agentmods.dev/badge/skills/microsoft/wassette/documentation/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/microsoft/wassette/documentation"><img src="https://agentmods.dev/badge/skills/microsoft/wassette/documentation.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 | $0.00049 | $0.00411 |
| Opus 5.5 | $0.00020 | $0.00164 |
| Sonnet 5.5 | $0.00010 | $0.00082 |
| Haiku 4.5 | $0.00005 | $0.00041 |
Grade A, and why
documentation 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 2mo 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.
What it actually says
documentation skill
Wassette documentation lives under docs/ and is built with
mdBook.
Build and serve
just docs-build # Build static HTML to docs/book/
just docs-watch # Serve at http://localhost:3000 with live reload
just docs-serve # Serve and open in the browser
Or directly: cd docs && mdbook serve / mdbook build.
URL structure
Production uses a multi-version layout that mdbook serve does not reproduce
locally:
- Local: open
http://localhost:3000/overview.html(or a specific page). The version picker and the root redirect only work in production. - Production:
https://microsoft.github.io/wassette/latest/(and/v0.3.0/for releases).
Writing style
- Prefer working code examples over long prose; explain details second.
- Keep pages focused and concise; every sentence should add value.
- Use active voice and present tense; define acronyms on first use.
- Always set the language on code blocks; use descriptive link text.
Visual changes
Preview layout or presentation changes locally. Include screenshots when they help reviewers understand a meaningful visual difference.
Adding a page
- Create the markdown file in the right
docs/subdirectory. - Register it in
docs/SUMMARY.mdso it appears in navigation. - Match existing structure and formatting; test all links.
- Preview locally with
just docs-serve.
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.
- 2mo ago First seen · 50 lines · 49 tokens per session scan A 9cc902d49fa9
documentation is a skill published in the GitHub repository microsoft/wassette (972 stars, last pushed 2d ago), licensed MIT. It adds 49 tokens to every session and 411 once invoked, about $0.0002 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.
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