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

With no annotations, the description carries the full burden and does well: it discloses a cost ('Spends credits'), a persistence side effect (saved to the account library), a scope exclusion (not placed on a card), and the return shape. It still omits auth/permission needs and any indication of latency or failure behavior.

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?

Three sentences, front-loaded with the core action and side effect, with cost and return details following logically. 'with a preview of each pose' partially restates 'poses like get_sprite,' a small redundancy.

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 correctly compensates by naming the return fields (imageUrl, poses, preview per pose). Cost, persistence, and the non-placement constraint are all covered, leaving only parameter detail and permission requirements unaddressed.

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%, so the schema already documents prompt and referenceUrl; the description adds no parameter-level meaning at all. The 'quality' enum (medium/high) has no description in either place, leaving its cost/quality tradeoff unexplained – hence the baseline 3 rather than a bonus.

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+resource ('Generate an asset sprite with AI') plus the persistence side effect ('save it to the account library'), which cleanly separates it from add_asset, update_asset, generate_background, and generate_mascot. An agent can identify the operation without opening the 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?

Provides an implicit when-not via 'Does not place it on a card,' which signals a boundary versus placement tools, and it references get_sprite for the output shape. However, it never states when to prefer this over add_asset or the other generate_* tools, so the routing is left to inference.

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