UML-MCP

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validate_uml

Read-onlyIdempotent

Check diagram type, format, code length, and basic syntax locally before render; returns errors and suggestions without calling Kroki.

Instructions

Validate diagram type, format, code length, and basic syntax locally before render (no Kroki call). Returns errors and suggestions.

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": {
      "diagram_type": "<diagram_type>",
      "code": "<code>"
    },
    "name": "validate_uml"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes	Diagram source text.
`strict`	No	When True, apply extra Mermaid/D2 checks (no extra PlantUML rules).
`diagram_type`	Yes	Same as generate_uml (see uml://types).
`output_format`	No	Intended output format (default svg); must be allowed for the type.	svg

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.0Sep 14, 2026

TDQS

A4.4/5.0

Behavior5/5

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

The description adds significant behavioral context beyond the annotations: it specifies local execution (no Kroki call), validates specific aspects (type, format, code length, basic syntax), and returns errors and suggestions. All annotations (readOnlyHint, idempotentHint, destructiveHint) are consistent.

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?

The description is a single, well-structured sentence that efficiently conveys the tool's purpose and key characteristics. No wasted words.

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

Completeness4/5

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

The description covers the primary validation scope and return type, and with the output schema present, further detail is unnecessary. It could be slightly more specific about 'basic syntax,' but overall it is complete for the tool's role.

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?

The input schema has 100% coverage with clear descriptions for each parameter. The tool description does not add any additional meaning to the parameters beyond what the schema already provides, so baseline score of 3 is appropriate.

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?

The description clearly states the tool validates diagram type, format, code length, and basic syntax locally before rendering. It distinguishes from sibling tools like generate_uml by emphasizing it is a pre-render validation step without a Kroki call.

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?

The description implies the tool should be used before rendering to check validity, and it notes it runs locally without a Kroki call. However, it does not explicitly state when not to use it or name alternative tools for comparison.

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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