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

Annotations only declare safety flags (readOnlyHint=false, destructiveHint=false), so the description carries the real behavioral load: it spends credits, is asynchronous with a specific polling endpoint and success condition (model.available), returns 402 and 409 in named failure modes, and requires the start_generation scope. That is far beyond what the structured fields provide.

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?

Front-loaded with purpose and cost, then prerequisites, then async/error behavior, then the scope. Dense and largely earned, though the parenthetical asides and the all-caps credit warning make it slightly heavy for two sentences of core content.

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 an async mutation with no output schema, the description supplies everything an agent needs: state eligibility, async delivery mechanism and terminal condition, error codes, cost/auth requirements, and retry semantics. Nothing material is missing.

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 both id and idempotency_key, and the description adds little on their syntax. It does add useful state context around which id values are eligible (confirmed vs. failed vs. ready), which is the baseline-plus level rather than a genuine augmentation of parameter meaning.

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+resource ('Start 3D generation') and immediately flags the cost, which distinguishes it from sibling generators like listGenerationOptions, createItem, and confirmScale. An agent can tell what it does and what it costs 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?

It gives explicit preconditions ('Requires status confirmed with confirmed dimensions'), explicit exclusions ('A ready item is never regenerated in place'), an allowed retry case ('a failed generation may be attempted again'), and names the alternative action (create a new item from the images). This is exactly the when/when-not/alternative structure.

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