combine

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

Annotations already declare destructiveHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral facts beyond them: the merge happens in world space, materials are preserved, and geometry is neither welded nor moved. It omits, however, that source objects are removed by default (delete_sources=true), which is the concrete destructive consequence.

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?

Three tight sentences, front-loaded with the core operation, followed by motivation and the key semantic caveat. No filler or repetition.

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?

There is no output schema, so the description should carry more weight. It covers purpose, timing, and geometry semantics well, but leaves the fate of the source objects (default deletion) and the naming of the result unexplained — significant omissions for a destructive mutation tool.

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 0% and the description says nothing about any of the three parameters. It never explains that `names` is the list of objects to merge, what `name` does (output object naming), or — most importantly — that `delete_sources` defaults to true and destroys the originals. With zero schema documentation, the description needed to carry this load and does not.

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 and resource ('Merge several meshes into one mesh object') and anchors it to a familiar reference behavior ('as Join (Ctrl+J) does in Blender'). It also contrasts the operation with siblings by clarifying it is not welding (vs `weld`) and not a positioning op (vs `move_to_contact`).

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 concrete when-to-use rule ('Do it before export to save draw calls') and routes a related need to an alternative ('use move_to_contact to close a gap'). It stops short of naming when NOT to combine, e.g. when separate objects are still needed downstream (vs `attach`/`parent`), but the guidance is clearly actionable.

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