join_objects

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

No annotations are provided, so the description carries the full burden; it does well by disclosing that geometry is unmodified, meshes stay separate inside the object, and the first name becomes the active object. It stops short of stating what happens to the source objects (whether they are removed), whether the operation is reversible, or how modifiers/parenting are handled.

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?

Front-loaded with the core action, then the tip and args; well ordered and easy to scan. The first two sentences restate the same idea ('keeps all geometry as-is' / 'without modifying geometry'), a minor redundancy that keeps it from a 5.

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?

For a single-parameter merge tool with an output schema present (so return values needn't be explained), the description covers action, scope, side-effect expectations, sibling routing, and parameter meaning. Nothing an agent needs to invoke it correctly is missing.

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?

With only one parameter and 0% schema coverage, the description compensates by explaining the list is object names to join and that 'the first name becomes the active object' — a non-obvious ordering semantic the schema does not convey. It doesn't clarify name-matching behavior (e.g. missing names) but adds real value over the bare array schema.

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+resource ('Join multiple mesh objects into one') and immediately names the sibling that is NOT the same operation (booltool_auto_union), so the agent can disambiguate without opening either schema. The parenthetical '(keeps all geometry as-is)' pins the scope further.

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?

Explicitly routes the agent: 'If you want to truly fuse overlapping meshes into one solid shape, use booltool_auto_union instead', and explains why (boolean union merges geometry and removes internal faces). The when-to-use-this vs the alternative is fully spelled out.

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