staruml-mcp

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generate_diagram

Generate UML diagrams in StarUML from Mermaid code. Supports class, sequence, flowchart, ER, mindmap, requirement, and state diagrams.

Instructions

Generate a UML diagram in StarUML from Mermaid code. Supported Mermaid diagram types: classDiagram, sequenceDiagram, flowchart, erDiagram, mindmap, requirementDiagram, stateDiagram. StarUML must be running with apiServer enabled.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "code": "<code>"
    },
    "name": "generate_diagram"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes	Mermaid diagram source code. Must start with one of: classDiagram, sequenceDiagram, flowchart, erDiagram, mindmap, requirementDiagram, stateDiagram. Example: "flowchart LR\n A[Start] --> B[End]"

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.3Jul 28, 2026

TDQS

A4.2/5.0

Behavior2/5

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

No annotations provided, so description carries full burden. It discloses the requirement for StarUML, but omits behavioral traits like whether the tool is destructive, idempotent, or requires specific permissions. It does not describe what happens to existing diagrams or whether it blocks on execution.

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?

Two concise sentences: the first states the purpose, the second lists supported types and a prerequisite. No wasted words; every sentence adds value.

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

Completeness5/5

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

For a single-parameter tool with no output schema, the description covers input format, supported types, and a prerequisite. It is sufficient for an agent to understand what the tool does and how to use it.

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

Parameters5/5

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

Schema coverage is 100% and description adds significant meaning: it specifies the valid starting strings for the 'code' parameter and provides an example. This goes well beyond the schema's minLength and type constraints.

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

Purpose5/5

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

Clearly states it generates a UML diagram in StarUML from Mermaid code, lists supported diagram types, and gives a prerequisite. The verb 'Generate' and resource 'UML diagram' are specific and unambiguous.

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

Usage Guidelines4/5

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

Provides clear context (generating diagrams from Mermaid code) and a prerequisite (StarUML must be running with apiServer enabled), but does not explicitly differentiate from sibling tools like 'create_diagram' or specify when not to use it.

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