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

Annotations declare readOnlyHint=false and destructiveHint=false, so the agent already knows this is a non-destructive mutation. The description adds real value beyond that with 'at the size it is' (scale is preserved) and the orientation rule for top on floor/ceiling surfaces. It says nothing about failure modes if the id is unknown or the target side is occupied.

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?

Two tightly written sentences with no padding, and the primary action is front-loaded before the orientation clarification. The economy is good; readability suffers only from the cryptic vocabulary rather than from length.

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 mutation tool with a nested parameter object, six-value enums, and no output schema, the description handles the genuinely confusing part (top orientation on floor/ceiling) and the size-preservation behavior. It is still incomplete about the class of objects this applies to and about when to prefer it over siblings.

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 67%: id and the nested 'on' object (including the layer/side floor-ceiling convention) are documented in the schema, but 'top' has no schema description. The description partially compensates by explaining that on a floor or ceiling, top indicates how the picture's top points, giving the enum meaning it otherwise lacks.

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 names a specific verb ('rehangs') and a constrained resource ('something placed on another block's side'), which does convey repositioning an existing object rather than creating one. However, the phrasing is idiosyncratic and never states plainly that this moves an object to a new location, and it draws no boundary against edit_object, add_object, or remove_object among the siblings.

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 tool versus edit_object or add_object/remove_object, and no prerequisites such as needing the object's id from the look tool. The description only implies usage through the verb 'rehangs'.

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