place_actor_on_terrain

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

Annotations declare a mutation (readOnlyHint=false) with no idempotency, and the description is consistent with that. It adds real value beyond the annotations by explaining the sampling mechanism, why traces are avoided, and exactly what gets mutated (the actor's Z, relative to either mesh bbox bottom or origin plus z_offset). It could still say more about failure modes (e.g., actor not found, out-of-bounds behavior) despite exposing in_bounds.

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 tight sentences lead with the purpose and the key constraint (no line trace) before the parameter details. The trailing returns block is verbose, but since no output schema exists it earns its place by documenting the response shape.

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?

With no output schema, the description compensates by listing the full return shape, and with 100% schema coverage plus annotations the safety profile is covered. It is nearly complete for a single-actor mutation; only error/failure behavior is left implicit.

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 schema already documents actor_name, align (with enum values), and z_offset. The description restates the align semantics rather than adding new meaning, so the baseline 3 applies.

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 gives a specific verb+resource ('Ground an actor on the landscape') and even the mechanism (heightmap sampling at the actor's XY, no line trace). It is clear what the tool does, but it never names or contrasts with siblings like snap_actor_to_ground or batch_place_actors_on_terrain, so it stops short of full sibling differentiation.

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?

The parenthetical 'no line trace; traces miss the landscape headless' implies when this approach is needed (headless/no-trace contexts), which is useful implied guidance. However, it never states when to prefer this over alternatives such as snap_actor_to_ground or batch_place_actors_on_terrain, and gives no prerequisites or exclusions.

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