Add Arc

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

The description discloses the key behavioral trait that this is a mutating operation by stating it saves the result in place. This complements the annotations (readOnlyHint=false, destructiveHint=false) and adds context about the target being an editable copy. It does not contradict the annotations.

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, focused sentence with no filler. It front-loads the action and context, and every word earns its place.

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 that the schema covers parameters, the annotations cover read-only/destructive hints, and an output schema exists, the description is nearly complete. It would be slightly stronger with an explicit note on when to use this over sibling add_* tools, but the editable-copy scope covers the main prerequisite.

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?

The free-text description does not explain any parameters, but the input schema already documents center, radius, start/end angles, file_path, and layer semantics ('Layer name (created if missing)'). Therefore the schema carries the parametric meaning, and the description adds no further value beyond the baseline.

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 uses a specific verb ('Draw') and resource ('an arc on the editable copy'), and clearly states the action's persistence ('save it in place'). This differentiates it from sibling tools like cad_add_line or cad_add_circle even without relying on the tool name.

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 establishes the correct context: the tool operates on the editable copy, not the original file. It does not explicitly name alternatives or exclusion conditions, but the editable-copy phrasing is a clear and sufficient usage signal.

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