staruml-mcp

Overview Schema Source Related Servers Discussions Admin

create_element

Creates a UML model element without placing it on a diagram. Specify the element type and parent element ID.

Instructions

Create a new UML model element (MODEL ONLY — not placed on any diagram canvas). For native typed diagrams (Use Case, Activity, Class), use create_element_with_view instead so shapes appear in the diagram. The 'type' is a metamodel class name. Requires staruml-mcp-extension to be installed in StarUML. Install from https://github.com/ezrabrilliant/staruml-mcp-extension

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": {
      "type": "<type>",
      "parentId": "<parentId>"
    },
    "name": "create_element"
  }
}

Input Schema

Name	Required	Description
`name`	No	Optional element name
`type`	Yes	Metamodel type, e.g. 'UMLClass', 'UMLPackage'
`parentId`	Yes	Parent element's _id

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.3Jul 28, 2026

TDQS

A4.1/5.0

Behavior3/5

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

No annotations are provided, so the description carries full burden. It states the tool only affects the model (not the diagram), but does not disclose other behavioral traits like error handling, permission needs, or whether it can overwrite existing elements. The description is adequate but not rich.

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

Conciseness4/5

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

The description is four sentences long, front-loaded with the main purpose and usage distinction. The installation instruction and link are useful but add slight length. Overall, it is structured and reasonably concise.

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?

Given the tool has 3 parameters and no output schema, the description covers the essential: what it does, when to use it (vs sibling), and a critical prerequisite. It does not mention return value, but that's often implicit for creation tools. The sibling list is large, but the description addresses the most relevant alternative.

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 description coverage is 100% (all three parameters have descriptions). The description adds that 'type' is a metamodel class name, which aligns with the schema. However, it doesn't add significant new meaning beyond the schema's own parameter descriptions.

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 creates a UML model element and explicitly notes it is model-only (not placed on diagram). It distinguishes from the sibling tool 'create_element_with_view', which does place shapes on diagrams.

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

Usage Guidelines5/5

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

The description provides explicit when-to-use vs. alternatives: 'For native typed diagrams... use create_element_with_view instead'. It also lists a prerequisite ('Requires staruml-mcp-extension to be installed') and includes an installation link.

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