Adds an arc to an explicit sketch reference using center, radius, and start/end angles to define curved sketch geometry.
Add an arc (center, radius, start/end degrees) to an explicit sketch reference.
| Name | Required | Description | Default |
|---|---|---|---|
| center | Yes | ||
| radius | Yes | ||
| end_angle | No | ||
| sketch_id | Yes | ||
| start_angle | No |
| Name | Required | Description | Default |
|---|---|---|---|
| object | Yes | ||
| status | No | success | |
| message | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. 'Add' implies a document mutation, but it says nothing about whether the sketch must be open/active, whether the operation is undoable via nx_undo, what happens with an invalid sketch_id or out-of-range angles, or any permission/state requirements.
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 front-loaded sentence with no filler; the geometry summary is placed immediately after the resource. It is efficient, though its brevity is partly the cause of the missing prerequisite details rather than a model of density.
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?
An output schema exists, so return values need not be explained. But for a state-changing sketch operation with zero annotation coverage, 0% schema description coverage, and 5 parameters, the description omits preconditions, failure modes, and the meaning of sketch_id — significant gaps for an agent to call it correctly.
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%, and the description names four of five parameters (center, radius, start/end angles) and importantly specifies that angles are in degrees, which the schema does not state. It does not explain sketch_id beyond 'explicit sketch reference', leaving one parameter undocumented in both places.
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 ('Add') and resource ('arc') scoped to a sketch, plus a parenthetical summarizing the geometry that defines it. It is distinguishable from nx_sketch_line and nx_sketch_circle by resource name, though it never explicitly contrasts itself with those siblings.
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?
No guidance on when to use this versus nx_sketch_circle (a full circle is just an arc of 360°) or the other sketch primitives. The phrase 'explicit sketch reference' hints that a sketch must already exist, but there is no stated prerequisite about obtaining sketch_id, being in sketch-edit mode, or finishing with nx_finish_sketch.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.