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

With annotations covering safety (readOnly, idempotent, non-destructive), the description still adds substantial behavioral context: a 4-per-call cap, image labelling by listing and index, 'attached: false' for images that fail to load, and the withdrawn-listing edge case returning only status. These are non-obvious output/error behaviors not present in structured fields.

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, then defaults, output labeling, failure marking, and an edge case. Dense but nearly every clause carries actionable information, though the single paragraph packs several concepts that could be split for scannability.

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?

No output schema exists, so return values must be explained—and they are: images, labels naming listing and index, attached: false for failed loads, and withdrawn listings returning only status. An agent has enough to call and interpret results correctly.

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 schema already documents parameters; the description adds the 4-per-call limit and default-first-4 behavior, and ties photo_indices to get_listing ordering. This goes slightly beyond the schema's own wording, warranting a bit above baseline.

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 and resource: 'Returns a live listing's photos as images to look at.' This is clearly distinguishable from get_listing (data) and search_listings, and the description explains the concrete purpose (visual verification of what ad text omits).

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?

Explains the default behavior ('first 4') and how to get others ('pass photo_indices'), plus the motivating use case (checking flooring, kitchen, bathroom, light, condition by eye). It stops short of explicitly naming when to use a sibling like get_listing instead, so no explicit alternative routing, but the context is clear.

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