download_ad_image

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

With no annotations, the description carries the burden and discloses that the result is an embedded binary resource plus a direct image preview. It also states supported formats and a 5 MiB size limit, and addresses URL expiry, though it omits auth or rate-limit details.

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 description is three tight sentences with no waste. It is front-loaded with the action and URL source, then provides return behavior, format/size constraints, and expiry guidance.

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 simple one-parameter download tool with no output schema or annotations, the description covers purpose, source of the URL, return format, supported image types, size limit, and expiry handling. This is enough for an agent to call it 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 0%, so the description must compensate for the single url parameter. It defines the URL as a Meta CDN image URL returned by specific sibling tools and adds the freshness/expiry requirement, which is meaningful beyond the schema's generic URI format.

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 uses a specific verb (Download) and resource (Meta CDN ad image), and explicitly ties it to URLs returned by named sibling tools (list_ad_images, get_ad_image, get_ad_creative). This clearly distinguishes it from metadata-retrieval siblings.

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 intended context: use URLs returned by the listed image/creative tools and avoid requiring the client to fetch the external URL. It also notes using a fresh URL if expired, though it does not explicitly describe when not to use it or name a fallback alternative.

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