place_instance

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

No annotations are provided, so the description carries the full behavioral burden, yet it says nothing about whether this mutates plate state, what happens on out-of-bounds coordinates or invalid instance indices, whether placement is absolute or additive, or what coordinate origin the bed uses. Only the unit (mm) and the fact that x/y refer to the object's centre are 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?

A single short sentence with zero waste, but it is under-specified rather than genuinely concise. The core information (unit and centre-anchor) is front-loaded correctly.

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 four-parameter, all-required mutation tool with no annotations, no output schema, and 0% schema description coverage, the description is too thin. It omits coordinate origin, error behavior on bad indices, and how the call relates to sibling object-manipulation tools.

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%, so the description must compensate, and it partially does: it clarifies that x/y are in millimetres and denote the centre rather than a corner, and it implies 'instance' selects one copy of a multi-instance object. It says nothing about object_id lookup semantics or valid ranges, leaving real gaps.

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 verb ('Fix the centre') and a resource ('one copy of an object on the bed'), which is enough to infer a placement operation. However, 'Fix the centre' is loose phrasing, and nothing distinguishes this from siblings like transform_object or arrange_plate, which also move objects on the plate.

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?

There is no guidance on when to use this versus transform_object, arrange_plate, or add_model, and no prerequisites or preconditions are stated. The agent must infer the usage context entirely from the name and sibling list.

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