draw_circle

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

With no annotations, the description must carry the full burden; it does disclose two non-obvious behaviors — that a diameter constraint is added automatically and that construction circles are excluded from the profile. It does not state preconditions (must a sketch already exist? does it need an active document/instance?) or what happens with an invalid sketch_index.

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 core purpose is front-loaded in one sentence, followed by a compact Args block. The extra clause on construction mode is short and earns its place by preventing a common misuse.

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 6-param mutation tool with no annotations, the description covers units, coordinate meaning, sketch targeting, construction mode, and the automatic constraint side effect, and an output schema exists to cover returns. The remaining gap is execution prerequisites (sketch/document/instance state), which an agent would still have to discover.

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 17% (only 'instance' is documented), so the description must compensate — and it does for five of six params: mm units for x/y/diameter, 'sketch_index 0 = latest sketch', and the construction semantics with a concrete PCD example. Only 'instance' is left to the schema, which already covers it.

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?

States a specific verb ('draw') and resource ('circle in a sketch') plus a defining behavioral trait: an automatic diameter dimension is added. An agent can distinguish it from draw_rectangle, draw_arc, and draw_polygon without inspecting any schema.

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 construction flag carries an explicit use case ('useful for showing bolt PCD without cutting'), which is genuine when-to-use guidance for that option. However there is no guidance on when to prefer this over draw_closed_profile or draw_slot, and no stated prerequisites such as needing an active sketch or connected instance.

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