Draw Circle

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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the mutate-but-non-destructive profile is covered. The description adds the useful fact that geometry lands in the implicit most-recent sketch, but says nothing about what happens when no sketch exists or about units of the radius.

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?

A single short sentence with zero filler, and the scope constraint is front-loaded where it matters. It is terse to the point of under-specification, but nothing is wasted or padded.

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 4-parameter geometry mutation with low schema coverage and no output schema, one sentence is thin: the coordinate frame, units, required preconditions (active sketch, create_sketch with z_offset to move the plane), and differentiation from draw_circles are all absent.

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 only 25%: center_z is well documented, but radius and center_x/center_y are bare. The description adds no meaning at all - no units, no indication that center_x/center_y are coordinates in the sketch plane - so it fails to compensate for the coverage gap.

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 ("Draw a circle") plus a scoping constraint ("in the most recent sketch"), so an agent knows the target is the active sketch rather than an arbitrary one. It does not distinguish itself from near-siblings like draw_circles or draw_arc, which prevents a 5.

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?

Implicit guidance: the phrase "most recent sketch" tells the agent a sketch must already exist and that the target is not selectable. It never states when to use this versus draw_circles (plural) or create_polygon, and gives no prerequisites or failure conditions.

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