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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds real context beyond them: images come from the last listing walk, the response reports whether the listing is live, suppressed/out-of-stock listings still return images, and Amazon-hosted images are fetched at a bounded size. Auth requirements and rate limits are not covered, keeping it at 4.

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 the core purpose and return shape, then constraints and the anti-misuse warning. Dense but every clause adds information; the middle sentence is slightly run-on but not wasteful.

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, 8 parameters and 13% schema coverage, the description needs to do heavy lifting and mostly does: it explains the return payload (pictures, links, slot order, live status) and the key parameter defaults. Gaps remain around the two connection/marketplace parameters and any pagination or error behavior.

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 only 13%, so the description carries most of the burden and does so well: it states asin or sku is required, max_images default 4 and ceiling 8, slots format (MAIN, PT01, ...), size_px default 800 and why it is bounded, and attach=false for links only. Only marketplace_id and seller_connection_id are left to the schema.

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 ('One product's listing images as PICTURES the assistant can look at, plus the stored links and slot order') and makes the multimodal return explicit, which no sibling tool does. An agent can tell this apart from product_library or ppc_creatives without opening a 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?

Gives clear usage context ('Reads the images on file from the last listing walk') and an explicit when-not rule: never switch to another product because a PDP is empty, since out-of-stock/suppressed listings still have images. It stops short of naming an alternative tool for other image needs, so not a 5.

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