v3.0.0 — Inline SVG rendering for Claude Desktop

SVG diagrams now render inline in Claude Desktop. generate_diagram returns SVG as normalized, theme-friendly markup text that scales cleanly in chat, instead of an image/svg+xml image block that the Anthropic API always rejected.

Breaking changes

• generate_diagram with format=svg returns the SVG markup as a text content block instead of an image/svg+xml image block. Claude Desktop (the Anthropic API) accepts only raster formats in image blocks, so the previous shape always failed with "unsupported format"; clients that render SVG image blocks now receive markup text instead.
• The advertised default for generate_diagram's format argument changed from png to svg, so callers that omit it now get the text/SVG path. Pass format: png explicitly for an image block.

Changed

• SVG output is normalized for inline chat rendering before being returned: the root element's background and fixed-size style declarations (including Mermaid's max-width) are stripped, the fixed width becomes width="100%" with a viewBox (synthesized from the pixel dimensions when missing or invalid) and style="height:auto" (the pixel height attribute is kept as an intrinsic-size fallback), and preserveAspectRatio is dropped in favor of the proportional default. Only the root tag is rewritten: this covers PlantUML-style root backgrounds; backgrounds painted inside the body (Graphviz's canvas polygon, Mermaid's embedded <style> rules) are left as-is.
• generate_diagram returns an error instead of inline SVG when the normalized markup exceeds 100 KB, pointing the caller at get_diagram_url or generate_png_diagram_with_custom_dpi, since text output is billed as model context tokens.
• Upgraded github.com/mark3labs/mcp-go from v0.25.0 to v0.58.0 (52 releases), migrating to the typed argument accessors API in place of raw Arguments map access.
• Raised the required Go toolchain to 1.25.5, updating go.mod, CI (actions/setup-go), and the Docker builder image accordingly.

Fixed

• Tool descriptions for the format argument no longer advertise text, which the schema enum and validation reject; they now list exactly svg and png.
• generate_png_diagram_with_custom_dpi now honors its declared default DPI of 150 when dpi is omitted, rejects a wrong-typed dpi instead of silently falling back to the default, and enforces a valid range of 72–300 consistently across the guard, the error message, and the parameter schema.
• Stdio server startup/runtime errors are now logged and cause a non-zero exit, except for a graceful SIGTERM/SIGINT shutdown (which surfaces as context.Canceled and now exits cleanly).
• Tool annotations are now declared on all three tools (generate_diagram, get_diagram_url, generate_png_diagram_with_custom_dpi) as read-only, non-destructive, idempotent, open-world; get_diagram_url previously advertised a self-contradictory idempotentHint: false, and destructiveHint: false was dropped from the wire due to omitempty on a plain bool.
• Mixed-case diagramType and format arguments are now normalized to lowercase before being forwarded to Kroki, instead of being validated case-insensitively but forwarded raw.
• Corrected the invalid-format error message to list the actually supported formats: format is required and must be one of: png, svg.
• svgconv.Convert now propagates PNG/JPEG encoding errors instead of discarding them and returning a truncated or corrupt image as success.

Full Changelog: v2.0.0...v3.0.0