extension-points

How extensions render as widgets inside other apps via named UI slots — the framework's VS-Code-style extension system. Use when a user asks to add a custom widget to an app surface (e.g. "add a sticky-note widget to my mail contact sidebar"), when wiring an ExtensionSlot in a template, or when marking an extension as installable into a slot.

Quality

96%

Does it follow best practices?

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Securityby

Passed

No findings from the security scan

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 body is a strong, actionable reference: lean and token-efficient with executable code and clearly sequenced workflows. Its only weakness is progressive disclosure — the material is a single inline file rather than an overview pointing into split reference files.

Suggestions

For a skill this size, move the detailed Lifecycle, Permissions, and Context contract sections into referenced bundle files (e.g. LIFECYCLE.md, PERMISSIONS.md) and keep SKILL.md as a concise overview with clearly signaled links, lifting progressive_disclosure to 3.

Consolidate the scattered back-compat callouts (EmbeddedTool, toolClassName, tool_slots/toolFetch aliases) into a single "Legacy names" subsection so each is stated once, reducing repetition across sections.

Add an explicit verification checkpoint at the end of the authoring workflow (e.g. "list-extensions-for-slot to confirm the install") to make the feedback loop explicit even though the operation is non-destructive.

Dimension	Reasoning	Score
Conciseness	The body is dense and assumes Claude's competence — it never explains what iframes, postMessage, Alpine.js, or polling are — and every section (tables, conventions, code) earns its tokens with no endorsement fluff, matching the lean score-3 anchor.	3 / 3
Actionability	Provides fully executable, copy-paste-ready guidance: a complete Alpine.js HTML snippet, exact action invocations ("add-extension-slot-target { extensionId: ... slotId: ... }"), and a concrete TSX <ExtensionSlot> example, satisfying the score-3 anchor.	3 / 3
Workflow Clarity	The authoring flow is a clear numbered 3-step sequence and the "Typical flow" section adds explicit conditional branching (install if it exists, otherwise create → target → install); the operations are reversible/per-user so the destructive-validation cap does not apply.	3 / 3
Progressive Disclosure	Sections are well-organized and cross-references to sibling skills are clearly signaled one level deep, but the ~200-line body is monolithic with no bundle files and content (Lifecycle, Permissions, Context contract) that could be split into referenced files is kept inline, fitting the score-2 rather than the "content appropriately split" score-3 anchor.	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 exemplary: it states concrete capabilities, includes a natural-language user trigger quote, and gives explicit "Use when..." guidance. It is specific, complete, and clearly distinguishable from related skills.

Dimension	Reasoning	Score
Specificity	Lists multiple specific concrete actions — "add a custom widget to an app surface", "wiring an ExtensionSlot in a template", and "marking an extension as installable into a slot" — matching the score-3 anchor rather than the single-action score-2 anchor.	3 / 3
Completeness	Explicitly answers both what ("How extensions render as widgets inside other apps via named UI slots") and when ("Use when a user asks to add a custom widget...") with explicit triggers, satisfying the score-3 anchor.	3 / 3
Trigger Term Quality	Includes a natural user quote ("add a sticky-note widget to my mail contact sidebar") alongside everyday terms like "widget", "app surface", and "slot", giving good coverage of phrases a user would actually say.	3 / 3
Distinctiveness Conflict Risk	Carves a clear niche (VS-Code-style named-UI-slot widget system) with distinct triggers unlikely to fire for sibling skills, rather than the overlapping score-2 anchor.	3 / 3
	Total	12 / 12 Passed

Validation

87%

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 — 14 / 16 Passed

Validation for skill structure

Criteria	Description	Result
metadata_version	'metadata.version' is missing	Warning
metadata_field	'metadata' should map string keys to string values	Warning

	Total	14 / 16 Passed

Repository: BuilderIO/agent-native
Path: .agents/skills/extension-points/SKILL.md
Commit: c1ee18b

Reviewed: 4 days ago

Table of Contents

Discovery Implementation Validation

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