echarts-mcp: Skill for Claude Code

echarts-mcp

Render Apache ECharts charts server-side (SVG + PNG + HTML, [email protected], stateless).

What this is for

This MCP server renders static charts for an LLM to inspect and iterate on. It produces SVG and PNG and a self-contained interactive HTML page (using a pinned client echarts CDN build fed the same option). The option JSON is identical between SSR and the browser, so it can also drive a fully live client-side chart.

Available tools

render_echart

Renders an ECharts option to one or more output formats. Returns the artifact(s) AND the echoed option.

• option (required) — a full ECharts v6 option object, passed through unchanged.
• formats — ["svg"] (default), or any subset/combination of "svg", "png", "html".
  • "svg" → raw SVG text (zero native deps).
  • "png" → base64 PNG image (needs the optional @napi-rs/canvas dependency).
  • "html" → a self-contained interactive HTML page.
• width / height — logical pixels (default 800×500).
• devicePixelRatio — DPI multiplier for PNG (default 2).
• theme — built-in name ("light", "dark") or an inline JSON theme object.
• background — "transparent" (default) or any CSS color.
• animation — false (default) for deterministic output.
• exportToUrl — persist the artifact and return a public URL (needs MCP_EXPORT_DIR + MCP_EXPORT_BASE_URL).

Example option:

{
  "xAxis": { "type": "category", "data": ["Mon", "Tue", "Wed"] },
  "yAxis": { "type": "value" },
  "series": [{ "type": "line", "data": [120, 200, 150], "smooth": true }]
}

validate_echart_option

Dry-run validate an option before rendering. Returns structural errors and semantic warnings (pinned to [email protected]) without producing an image.

list_chart_types

List common series types (line, bar, pie, scatter, sankey, …) for discoverability. Not an allowlist — render_echart accepts any ECharts v6 option.

Security notes

• Remote images are disabled by default (SSRF). A PNG option that references an image://https://… URL is rejected unless the host is allowlisted via MCP_IMAGE_ALLOW_HOSTS (comma-separated exact hostnames). Inline data: images work.
• option/theme are bounded (depth ≤ 64, ≤ 100k nodes); pathological inputs fail fast rather than degrading the local process.