cad_sketch_begin

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

With no annotations, the description mentions returning a sessionId and implies a state change, but lacks details on side effects, permissions, or lifecycle of the session.

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?

Two concise sentences with front-loaded key information, no filler words.

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 6 parameters (3 required), no output schema, and no annotations, the description is insufficient; it fails to explain required identifiers or the session's scope.

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?

Only two of six parameters (plane and face) are explained; the required documentId, workspaceId, and elementId are not described, and the optional name is omitted.

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 action (open a sketch session) and the target (standard plane or existing face), distinguishing it from sibling sketch tools like cad_sketch_line which operate within an existing sketch.

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?

It explains two usage modes (plane vs. face) and provides a source for the face id, but does not explicitly state when not to use this tool or mention prerequisites like having a valid element.

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