UML-MCP

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generate_uml

Idempotent

Generate UML, Mermaid, D2, and other diagrams from diagram type and code, returning rendered SVG, PNG, PDF, JPEG, or base64 for AI assistants via MCP.

Instructions

Generate any UML or diagram by type (class, sequence, mermaid, d2, etc.)

Input Schema

TableJSON Schema

Name	Required	Description	Default
`code`	Yes	Diagram code in the syntax for the chosen type
`scale`	No	Scale factor for SVG only (default 1.0, min 0.1). Ignored for other formats.
`theme`	No	PlantUML theme for UML diagrams (e.g. cerulean)
`output_dir`	No	Directory to save the image. Omit or None for URL, playground, and content_base64 only (no file write; use in serverless / read-only).
`diagram_type`	Yes	Type of diagram (class, sequence, activity, mermaid, d2, etc.)
`output_format`	No	svg, png, pdf, jpeg, txt, or base64 (default: svg). See uml://formats per type.	svg

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.0Sep 14, 2026

TDQS

B3.3/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations provide idempotentHint and destructiveHint. Description adds no further behavioral detail beyond generating diagrams, which is already clear. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence, front-loads purpose, no wasted words. Efficient and clear.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 6 parameters and output schema, description is sparse. Lacks context about output format options, file saving ability, or relationship to siblings. Output schema partly compensates.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with parameter descriptions. Tool description only hints at diagram_type via examples, adding minimal value beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states the tool generates UML or diagrams by type, with examples. It distinguishes the action from siblings like validate_uml but does not explicitly differentiate from generate_uml_batch.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool versus siblings. No mention of batch generation or validation alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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