create_offset_plane

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

With no annotations provided, the description carries the behavioral disclosure burden. It explains the nature of the created object, the offset sign convention ('Positive follows the reference outward normal; negate or set flip to invert'), and the key downstream behavior of passing the feature_id as a sketch faceId. It does not discuss permissions or document side effects, but the core behaviors of this construction-plance creation tool are clearly disclosed.

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 four dense sentences with no filler. Each sentence earns its place: the definition, the motivating use case, the parameter-mode selection, and the downstream usage. It is front-loaded with the core purpose and avoids repeating obvious schema field semantics.

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?

The description is strong overall, but it never explicitly states that exactly one of `plane` or `referenceFaceId` must be provided; the schema lists both as optional, so an agent could satisfy all required fields and omit the reference entirely, resulting in an invalid call. There is also no output schema, so the only return-behavior guidance is the implicit `feature_id` mention, which could be more explicit.

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 100%, so the baseline is 3, but the description adds substantial semantic value beyond the schema. It clarifies how to choose between `plane` and `referenceFaceId`, notes that `referenceFaceId` comes from `list_entities`, gives unit and direction examples for `offset`, and explains the returned feature_id's role in sketch primitives.

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 names a specific verb and resource: 'Create an offset construction plane: a datum plane parallel to a reference plane or face, shifted by a signed distance.' It also distinguishes this from sketch tools by explaining that the new plane becomes a sketch target, so an agent can tell it apart from siblings like create_sketch or create_extrude.

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 gives explicit when-to-use guidance: 'Use when you need to sketch at a specific Z (e.g. 2.5 mm above the Top plane) without an existing face there.' It also explains the two modes of use, plane vs referenceFaceId, and the downstream sketch-target behavior. It doesn't explicitly name alternative tools or state a formal 'do not use when', but the use case is clear and there is no sibling plane-creation tool.

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