architecture

Use when navigating the codebase for the first time, adding a new client method, adding a new container handler/service, or understanding how a request flows from Worker through the Sandbox DO into the container. Covers the three-layer architecture, client pattern, container runtime structure, and monorepo layout. (project)

1.97x

Quality

—

Does it follow best practices?

Impact

95%

1.97x

Average score across 3 eval scenarios

Securityby

Passed

No known issues

Quality

Content

92%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The content is a lean, actionable architecture reference with concrete paths and a clear change workflow, but it is monolithic: everything lives inline in SKILL.md with no progressive disclosure via reference files.

Suggestions

Move detail-heavy sections (e.g. request-flow diagrams, container-runtime internals) into reference files under references/ and link to them one level deep, keeping SKILL.md as a concise overview.

Add a short validation checkpoint to the Dockerfile-modification guidance (e.g. rebuild and smoke-test the image) to mirror the verification step already present in the control-operation workflow.

Trim the duplicated request-flow narration so the primary and compatibility paths are presented once with a clear contrast rather than restated across sections.

Dimension	Reasoning	Score
Conciseness	The body is dense with project-specific facts (package paths, class names, port numbers) and avoids explaining concepts Claude already knows; every section earns its place, though the two request-flow diagrams introduce minor redundancy.	3 / 3
Actionability	Concrete file paths (e.g. 'packages/sandbox/src/container-control/'), named classes, and a numbered procedure for adding a control operation give copy-paste-ready, executable guidance.	3 / 3
Workflow Clarity	The 'When adding a new container control operation' section is a clearly sequenced four-step procedure ending in an explicit verification step (unit tests on both sides plus an E2E test).	3 / 3
Progressive Disclosure	Sections are well organized, but the entire architecture reference is inline in SKILL.md with no bundle files or one-level-deep references to split out detail-heavy portions like the request-flow diagrams or container-runtime internals.	2 / 3
	Total	11 / 12 Passed

Description

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.

The description is specific, trigger-rich, and clearly answers both what the skill covers and when to use it, with a distinct architectural niche. The trailing '(project)' tag is a minor cosmetic oddity but does not weaken the trigger guidance.

Dimension	Reasoning	Score
Specificity	Lists multiple concrete actions such as 'adding a new client method', 'adding a new container handler/service', and 'understanding how a request flows from Worker through the Sandbox DO into the container', matching the multi-action anchor.	3 / 3
Completeness	An explicit 'Use when...' clause supplies the when, and 'Covers the three-layer architecture, client pattern, container runtime structure, and monorepo layout' supplies the what, answering both clearly.	3 / 3
Trigger Term Quality	Natural developer-facing triggers like 'navigating the codebase for the first time', 'adding a new client method', and 'adding a new container handler/service' are phrases a user would plausibly say when needing this skill.	3 / 3
Distinctiveness Conflict Risk	Domain-specific terms (Sandbox DO, Worker, container, three-layer architecture) carve a clear niche unlikely to trigger unrelated skills, despite the somewhat generic opening phrase.	3 / 3
	Total	12 / 12 Passed

Validation

100%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository: cloudflare/sandbox-sdk
Commit: ebb7be9

Reviewed: 4 days ago

Table of Contents

Discovery Implementation Validation

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.