open_documentLoad an existing FreeCAD .FCStd file and set it as the active document, returning its name and object list.
Open an existing .FCStd file, make it active. Returns doc name and object list.
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the annotations, the description discloses a meaningful side effect ('make it active') and the return content ('Returns doc name and object list'). This helps the agent anticipate the tool's state-changing behavior, although it does not describe error handling or behavior if the file is already open.
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 a single sentence that front-loads the core action, notes the activation side effect, and states the return values. Every phrase contributes useful information with no redundancy or filler.
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?
For a tool with one parameter and no output schema, the description covers the intended effect, the target file type, activation behavior, and the returned data. It does not cover failure modes or workspace interactions, but the tool appears simple enough that the provided information is sufficient for correct invocation in most contexts.
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?
Schema description coverage is 0%, so the description is the only source of parameter meaning. It identifies the path as referring to an existing .FCStd file, which gives basic context for the single required 'path' parameter. It does not specify absolute vs relative paths, supported file variants, or path resolution details, but for a single obvious string parameter this is adequately informative.
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 states a specific verb and resource: 'Open an existing .FCStd file, make it active.' This clearly distinguishes the tool from siblings like new_document, list_documents, and set_active_document by emphasizing both opening from an existing file and activating it. The purpose is unambiguous.
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 implies usage context: call this when an existing .FCStd file must be loaded and made active, rather than creating a new document. However, it does not explicitly name alternatives or state when not to use it, leaving the agent to infer the boundary against tools like set_active_document or new_document.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.