Merge elements

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

With annotations already declaring destructive and idempotent behavior, the description adds valuable context: the undo path, the return shape, and the error condition when an element is not editable. It still does not explain all side effects on the original elements or any permission requirements, so it is strong but not exhaustive.

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 front-loaded with the operation and its visual effect, then efficiently adds prerequisites, undo guidance, and return/error behavior. Every sentence carries useful information, with no filler or redundancy.

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 there is no output schema, the description fully covers the return shape and error semantics, plus the undo path and minimum element requirement. An agent has enough to invoke the tool correctly and interpret the result.

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 100%, so the single parameter is fully documented in the schema itself. The description's 'Needs at least two elements' mirrors the schema's minItems constraint without adding format, ordering, or other meaning beyond what the schema provides. Baseline 3 is appropriate.

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 ('Merges') and resource ('construction elements'), plus the visual effect so 3D bodies and sections display as one without contour lines, with an example ('slabs of the same material'). It does not, however, explicitly distinguish this from sibling operations like group_elements or solid_operation, so it falls short of a full 5.

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?

Gives a prerequisite ('Needs at least two elements') and names the undo alternative ('Undo with unmerge_elements'). The usage context is clear, including when a merge is appropriate (slabs of the same material), but it does not state when not to use this tool or compare it directly with other element-combining siblings.

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