get_prim_face_count_tree

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context about what each node returns (per-mesh face/vertex/triangle counts, per-group subtree_faces totals), though it omits any warning that counting faces over a deep tree may be expensive on large scenes.

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 short sentences, front-loaded with the core purpose and followed by the sibling comparison. Slight redundancy between the first line and the 'each mesh shows...' clause, but nothing is wasted.

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 an output schema present, the description needn't detail return values, and the two parameters are fully documented in the schema. The only meaningful gap is absence of any performance/cost note for deep or large trees, which matters for a face-counting traversal.

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 root and max_depth are fully documented in the schema. The description adds no additional meaning about these parameters (no guidance on depth cost tradeoffs), 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?

States a specific verb and resource ('Get scene tree with face counts per mesh and subtree totals') and explicitly distinguishes itself from the sibling get_scene_tree by scope. An agent can pick between the two without opening either schema.

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?

Names the closest alternative (get_scene_tree) and gives the condition that selects this one: geometry budget / face counts. It stops short of explicit when-not guidance (e.g., 'don't use for single-mesh stats, use get_mesh_stats'), but the routing signal is clear.

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