FreeCAD MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behaviors: the script runs in FreeCAD's interpreter context with access to specific modules (FreeCAD, FreeCADGui, App, Gui, doc), and stdout/stderr are captured and returned. However, it lacks details on potential side effects, error handling, or security implications, which could be important for an 'escape hatch' tool.

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

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

The description is appropriately sized and front-loaded. The first sentence states the core purpose, followed by context, output behavior, usage guidelines, and parameter details. Every sentence adds value without redundancy, making it efficient and well-structured.

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

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

Given the tool's complexity (executing arbitrary code) and lack of annotations or output schema, the description does a good job of covering context. It explains the execution environment, output capture, and usage scenarios. However, it could be more complete by addressing potential risks, performance implications, or example return formats, which are important for such a powerful tool.

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

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

The input schema has 0% description coverage, so the description must compensate. It adds meaningful semantics: 'script: Python code to execute.' This clarifies the parameter's purpose and format beyond the schema's basic string type. However, it doesn't provide examples, constraints, or best practices for the script content.

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

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

The description clearly states the tool's purpose: 'Execute arbitrary Python code in FreeCAD's interpreter context.' It specifies the verb ('execute'), resource ('Python code'), and context ('FreeCAD's interpreter'), distinguishing it from sibling tools that perform specific operations like analyzing shapes or listing documents.

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

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

The description explicitly provides usage guidelines: 'Use this as an escape hatch for operations not covered by the specific tools above. For example: creating objects, modifying properties, running macros, or accessing FreeCAD APIs not yet exposed as tools.' This clearly indicates when to use this tool versus alternatives, including specific examples and exclusions.

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