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

Beyond the readOnly/idempotent annotations, it discloses the async render-and-retry cycle with a concrete ~20 second cadence, the cached-results behavior per target kind, the flat-preview fallback when no 3D view exists, and the auth requirement plus what happens without a session. That is exactly the context annotations cannot carry.

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?

The core return value and the polling instruction are front-loaded in the first two sentences. The auth note is placed last, which is correct priority ordering, though the middle sentence is long and carries several ideas in one clause chain.

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 single-parameter, nested-target tool with a full output schema, the description covers everything the schema cannot: latency/retry, fallback output, caching, and authentication. An agent could invoke this correctly on the first try.

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 100%, so the baseline is 3, but the description adds genuine meaning by explaining why the target kind matters — an order job vs. a cart/quote line take different render paths. It does not elaborate on side or design, but the schema already documents those.

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 names a specific resource (the 3D mockup of a line's artwork on the product) and its delivery form (an image), so the agent knows exactly what it gets back. No sibling tool offers mockups, so there is no ambiguity to resolve, and the three target kinds are distinguished from one another.

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 states the operational context clearly: call it for an order job or a cart/quote line, and call again in about 20 seconds if the response says it is still rendering. It does not name an alternative tool or an explicit when-not-to-use case, which keeps it just below the top score.

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