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

Annotations only state it is a non-read-only, non-destructive, non-idempotent, closed-world write; the description adds substantial behavior the annotations cannot: concrete pricing (20 per sheet + 10 per cut), that estimate_only costs nothing, that each piece gets a free view check with failure reporting and a redraw offer, that nothing else is charged (no rotations/animations), and that all cut-outs are reframed to a uniform pixel height with world_height metadata.

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?

Purpose and the cost/estimate escape hatch are front-loaded, which is good, but the body is a single dense run-on paragraph packing view semantics, sheet planning, pricing, view checks, tier gating, return value, world_height behavior and export guidance into one block. The content mostly earns its place, yet the lack of separating structure makes it harder to scan than it needs to be.

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 complex 7-parameter generation tool with no output schema, the description covers cost, prerequisites, the returned set_id, follow-up tools (add_to_asset_set, export_godot_spriteframes, rotate_sprite, animation tools) and the sizing model. The notable gap is execution semantics — nothing about whether the call is long-running or needs check_generation polling before the set is usable.

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 86%, so the schema already carries most parameter meaning; the description still adds real value by spelling out what each view enum actually looks like (side profile facing right at eye level, ~45° top-down RPG, straight-down, isometric) and by explaining sheet density planning (~3-4 characters, 4-6 objects or 3 tall props per sheet). world_height and the reference/size interaction are also clarified in prose rather than left to the schema alone.

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 opens with a specific verb and deliverable: 'Make a whole matching game art set in the game's CAMERA VIEW' and enumerates the resource types (characters, props, tiles) plus the pipeline (GPT-Image sheets, cut into one asset per item, tagged with dimension and facing). It is clearly distinguishable from siblings like generate_items, generate_image and generate_animation_set because it stresses the coherent matching set and view-aware tagging.

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?

It gives clear operating guidance: pass estimate_only to see plan and price first, 'Voidless+ only', use add_to_asset_set to extend later, use style_asset_id or the first sheet to lock style, and use export_godot_spriteframes (not guessing) to size pieces in a game. It does not explicitly say when to prefer this over generate_items or generate_image for a single asset, so it stops short of full when/when-not alternates.

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