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

With no annotations and no output schema, the description carries the full burden. It does usefully disclose that the URLs are 'self-generated placeholder' images (i.e., synthetic, not real assets) and that rights notes accompany them, which is genuine behavioral context. However, it says nothing about auth needs, pagination, or whether the placeholder URLs are actually consumable.

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?

A single efficient sentence that front-loads the resource and content. It earns its words, though its terseness is partly under-specification rather than tight writing.

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 3-parameter tool with 0% schema coverage, no annotations, and no output schema, the description is thin: limit behavior, what 'types' accepts, and the shape of the returned block are all unaddressed. The rights-notes mention is a start but the definition is not complete enough for confident invocation.

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 0%, so the description must compensate. It partially does by naming media kinds (photo, video poster, spin) that plausibly map to the 'types' parameter, but it never mentions the 'types' filter itself, nor the 'limit' parameter (default 50) or the listing_id requirement.

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?

It identifies the resource (a media block tied to a listing) and enumerates the content (photo, video poster, spin, rights notes), but it is written as a noun-phrase fragment with no verb, so the action (retrieve media for a listing) is only implied. There is no media sibling to distinguish from, so the lack of differentiation is not a major issue.

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?

The description gives no when-to-use guidance, no prerequisites, and never names an alternative tool. 'For a listing' weakly implies listing_id must be supplied, but nothing tells an agent when this is the right call versus get_listing or search_inventory.

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