viceroy
Runs Fastly Compute WASM applications locally with Viceroy, specifically for Rust and Component Model projects. Use when starting a local Fastly Compute dev server with Viceroy, configuring fastly.toml for local backend overrides and store definitions, running Rust unit tests with cargo-nextest against the Compute runtime, debugging Compute apps locally, adapting core WASM modules to the Component Model, or troubleshooting local Compute testing issues (connection refused, missing backends, store config). For non-Rust Compute work or understanding the Compute API, prefer the fastlike skill instead — its source code is easier to understand as a Fastly Compute API reference.
76
93%
Does it follow best practices?
Impact
—
No eval scenarios have been run
Advisory
Suggest reviewing before use
Quality
Discovery
100%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is an excellent skill description that is highly specific, includes rich trigger terms, clearly delineates both what the skill does and when to use it, and even proactively disambiguates from a related skill. The concrete mention of tools (Viceroy, cargo-nextest), file formats (fastly.toml, WASM), and common error scenarios (connection refused, missing backends) makes it very easy for Claude to select this skill accurately.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: running WASM apps locally with Viceroy, configuring fastly.toml for backend overrides and store definitions, running Rust unit tests with cargo-nextest, debugging Compute apps, adapting core WASM modules to Component Model, and troubleshooting specific issues. | 3 / 3 |
Completeness | Clearly answers both 'what' (runs Fastly Compute WASM apps locally with Viceroy for Rust/Component Model projects) and 'when' with an explicit 'Use when...' clause listing six specific trigger scenarios. Also includes a helpful disambiguation clause directing to the 'fastlike' skill for non-Rust work. | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms users would say: 'Viceroy', 'Fastly Compute', 'WASM', 'Rust', 'Component Model', 'fastly.toml', 'cargo-nextest', 'local dev server', 'connection refused', 'missing backends', 'store config'. These are highly specific terms a developer would naturally use. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive with a clear niche (Viceroy + Rust + Fastly Compute local development). The explicit disambiguation from the 'fastlike' skill further reduces conflict risk by drawing a clear boundary between the two related skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
87%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a well-structured skill that efficiently communicates essential information about Viceroy. The gotchas section adds genuine non-obvious value, the quick start is immediately actionable, and the reference table provides excellent progressive disclosure. The main weakness is the lack of validation/verification steps in the workflow, particularly given that configuration issues are highlighted as common problems.
Suggestions
Add a validation step after 'viceroy -C fastly.toml bin/main.wasm' such as checking for expected output or a curl command to verify the server is running (e.g., 'curl http://127.0.0.1:7676/ to verify').
Consider adding a brief troubleshooting checkpoint in the quick start for the most common failure mode (missing [local_server] section) with expected error output.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The content is lean and efficient. The brief intro sentence is borderline unnecessary but very short. The gotchas section adds genuine value with non-obvious information (port differences, config requirements). No concepts are over-explained. | 3 / 3 |
Actionability | Provides fully executable commands for installation, building, and running Viceroy. The quick start section is copy-paste ready with concrete commands and comments explaining each step. | 3 / 3 |
Workflow Clarity | The quick start provides a clear sequence of steps, but there are no validation checkpoints or error recovery guidance. For a tool where misconfiguration (missing backends, missing local_server section) is called out as a common gotcha, a validation step would be valuable. | 2 / 3 |
Progressive Disclosure | Excellent structure with a concise overview, quick start, and a well-organized reference table pointing to four clearly-labeled one-level-deep reference files with 'Use when...' descriptions for easy navigation. | 3 / 3 |
Total | 11 / 12 Passed |
Validation
100%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- Repository
- fastly/fastly-agent-toolkit
- Commit
e0f4205
- Reviewed
Table of Contents
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