add_mirror

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

With no annotations, the description carries the full burden and does well: it discloses the merge behavior of a body mirror, the failure mode and its guarantee ('Fails, leaving the part as it was, when a copy would land outside the part'), and the resulting dimension name 'plane_offset'. It does not state prerequisites such as requiring an open part or the effect on pre-existing features.

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?

Content is front-loaded and every sentence carries information, but the plane/offset explanation is dense and split awkwardly across line breaks, forcing a re-read. Slight tightening would improve it without losing substance.

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?

No output schema and no annotations, so the description must stand alone, and it covers inputs, merge semantics, failure behavior, and the produced dimension. The main remaining gap is the absence of any precondition (e.g., an open part) or interaction with existing features.

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%, so the description must compensate and largely does: it explains that plane accepts 'front'/'top'/'right', a z/y/x offset, or another plane name moved along its normal, that offset_mm is that displacement, and that features takes list_features names whose copies follow their seeds. Only the 'name' parameter is left 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 opens with a specific verb and resource ('Mirror features, or the whole body') and immediately bounds the scope by plane type and offset. An agent can distinguish this from the pattern siblings (add_linear_pattern, add_circular_pattern) without opening 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?

It gives a concrete usage scenario: 'Without features the body is mirrored and merged: model half of a symmetric part, mirror it about the face where the halves meet.' That tells the agent when the no-features path applies, but no alternative tool is named for cases where mirroring is not the right operation.

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