google ads list image assets

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

Beyond the readOnly/openWorld/idempotent annotations, it discloses that URLs are stable and publicly served, that no delivery concept exists, that results are newest-first, and that the response count is the account total rather than the returned page size. These are valuable behaviors an agent cannot infer from the annotations alone.

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 dense but every clause earns its place: it states the core behavior, the important ordering/count caveat, the key alternative service, and the Merchant Center exclusion. Information is front-loaded with the most actionable facts first, and the caveats and disambiguation follow naturally.

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 read-only listing tool with a rich input schema and an output schema present, the description covers the behavioral context that is not already structured: URL stability, the library's timeless all-stock nature, ordering, response count semantics, and alternative sources. An agent has everything needed to invoke 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 100%, so the baseline is 3; the description adds useful nuance about limit behavior ('newest first, so a limit returns recent assets rather than an arbitrary slice'). However, it does not add semantic detail for filters like nameFilter, minWidth, minHeight, or beforeAssetId beyond what the schema already provides.

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, a precise resource (the account's image asset library), and the returned fields (URLs on tpc.googlesyndication.com, dimensions, file size, mime type). It also contrasts itself with video assets, PMax delivery galleries, and Merchant Center product imagery, so an agent can clearly tell it apart from 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?

Explicitly says the library is the whole stock with no delivery notion, which signals when to use it for complete library views. It names the hosted GetMCPAds service as the alternative for a visual-only delivery-aware gallery and rules out Merchant Center product imagery, giving concrete when/not-to-use guidance.

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