chart-image

Generate publication-quality PNG chart images from data, supporting line, bar, area, candlestick, pie, and heatmap charts. Triggers when the user asks to visualize data, create a graph, plot a time series, or generate a chart for a report, alert, or dashboard. Runs as a lightweight, headless Node.js process without a browser.

Quality

82%

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Securityby

Critical

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Quality

Content

65%

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

The body is highly actionable with executable examples throughout, but it is verbose and could be tightened, lacks validation checkpoints around chart generation and delivery, and keeps a large reference inline rather than progressively disclosing it into a separate file.

Suggestions

Trim the repeated command blocks: show one canonical example per chart type and consolidate the rest into the options reference rather than restating the same invocation pattern many times.

Add a validation checkpoint before sending the image — e.g., confirm the output PNG exists and is non-empty before invoking the send action — and note how to surface chart.mjs errors.

Move the large Options Reference tables into a separate REFERENCE.md (or a references/ file) and link to it from SKILL.md so the main file stays a concise overview.

Dimension	Reasoning	Score
Conciseness	The body is mostly efficient executable examples, but it is long and repeats near-identical command patterns across many chart types, and the extensive options tables plus a dated footer ('Updated: 2026-02-04') add tokens that could be tightened.	2 / 3
Actionability	Provides fully executable, copy-paste-ready node commands with concrete data examples for every chart type, plus a complete options reference table and a working setup command.	3 / 3
Workflow Clarity	Usage is sequenced (setup -> generate -> send image), but the 'always send the image' delivery step has no validation that the PNG was actually produced before sending, and there is no error-handling/checkpoint for the generate step.	2 / 3
Progressive Disclosure	Content is well-sectioned within a single SKILL.md, but the only bundle file (scripts/chart.mjs) is referenced only via commands; the large options reference is inline rather than split into a separate reference file, and there is no navigation pointing to bundle contents.	2 / 3
	Total	9 / 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, uses natural trigger phrasing, and clearly answers both what the skill does and when to use it. It is concise yet comprehensive and well-distinguished from other skills.

Dimension	Reasoning	Score
Specificity	Lists multiple concrete actions — 'Generate publication-quality PNG chart images from data, supporting line, bar, area, candlestick, pie, and heatmap charts' — and specifies the runtime environment ('lightweight, headless Node.js process without a browser').	3 / 3
Completeness	Explicitly states both what it does (generate PNG chart images) and when to use it via the 'Triggers when the user asks...' clause, satisfying the 'Use when' requirement.	3 / 3
Trigger Term Quality	Includes natural user phrasings like 'visualize data, create a graph, plot a time series, or generate a chart for a report, alert, or dashboard' — good coverage of terms users actually say.	3 / 3
Distinctiveness Conflict Risk	The niche is narrow and clearly scoped (PNG chart image generation via headless Node.js), with triggers tied to visualization/graph/plotting requests, making it unlikely to fire for unrelated skills.	3 / 3
	Total	12 / 12 Passed

Validation

93%

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 — 15 / 16 Passed

Validation for skill structure

Criteria	Description	Result
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	15 / 16 Passed

Repository: zebbern/claude-code-guide
Path: skills/chart-image/SKILL.md
Commit: af7d491

Reviewed: about 9 hours ago

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