fusion_sketch_add_circle

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

With no annotations, the description carries the full burden of behavioral disclosure. It only states the action and parameters, but does not mention side effects (e.g., modifying the sketch), error conditions, coordinate system conventions, or required states (like sketch existence). It fails to disclose any constraints (e.g., radius must be positive) or what happens if inputs are invalid.

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 concise sentence, front-loaded with the primary action and immediately clarifying the parameters. There is no wasted or redundant information; it earns its place entirely.

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 simple add-circle operation with 4 required parameters, the description covers the core semantics but omits sketch_id and any prerequisites or return behavior. Since there are no annotations and no output schema, the description should have provided a bit more context, such as stating that the circle is added to the referenced sketch or any validation details. It is adequate but leaves notable gaps.

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 coverage is 0%, so the description must compensate. It explains cx and cy as the center and radius_mm as the radius in mm, which adds meaning beyond the schema. However, sketch_id is not described at all, leaving a required parameter undefined. The description partially covers 3 of 4 parameters, but not fully, and units for cx/cy are only implied.

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: adding a circle to a sketch, with specific parameters (center coordinates and radius). It differentiates from sibling sketch tools like fusion_sketch_add_line or fusion_sketch_add_rectangle by specifying the geometric shape. The verb 'add' and resource 'circle' are precise, and the context (sketch) is explicit.

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 when a circle is needed in a sketch, but does not explicitly provide when-to-use vs alternatives, prerequisites (like an active sketch), or exclusions. It offers no guidance on when not to use this tool or mention alternative approaches. Only implied from the action itself.

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