silhouette_add_circle

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

Annotations already declare this as a non-read-only, non-idempotent, non-destructive local mutation, so the safety profile is covered. The description adds a genuinely useful behavioral fact beyond that: the shape is exported as a true DXF CIRCLE rather than a tessellated approximation. It does not disclose whether the design must pre-exist, whether repeated calls stack shapes, or how the shape interacts with layers.

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 short sentences with the core operation front-loaded and the export-format detail second. No filler, no repetition of the name, and nothing that could be trimmed without losing information.

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 mutating tool with six undocumented parameters, no output schema, and no annotation help on parameters, the description is too thin. An agent still has to guess what 'design' refers to, what values 'layer' accepts, and what 'label' is for before it can call this confidently.

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% across 6 parameters, so the description carries the full burden and only partially meets it. It clarifies the meaning of cx_mm and cy_mm as the circle's centre, but radius_mm, design, label, and layer (with its non-obvious 'CUT' default) are left entirely unexplained.

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 ('Add a circle') and pins the anchoring point to cx_mm/cy_mm, which clearly separates it from sibling shape creators like silhouette_add_ellipse or silhouette_add_rectangle. It falls short of 5 because it never explicitly contrasts itself with those siblings or states which design the circle goes into.

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?

There is no when-to-use guidance, no prerequisite such as an existing design created via silhouette_new_design, and no mention of alternatives or when this tool should be avoided. The agent must infer all invocation context from the sibling list.

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