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

The annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world) and the schema documents the 404/403 failure modes, so the description is not obligated to restate them. What it adds is return-content context (the ad's metrics and provenance), which is useful but is output description rather than operational behavior such as auth, rate limits, or side effects.

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?

Two sentences, front-loaded with the resource and its contents, then the id provenance. Every clause carries content, though the dense parenthetical lists make it slightly heavy to parse.

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 and only two fully-covered parameters, the description is the sole source of return-value information and it delivers: it names the entity, its fields, and the attribution data returned. Combined with the id-provenance guidance and the sibling route, nothing an agent needs to call this correctly is missing.

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, but the description goes further by explaining how to obtain ad_id (latest_ad_id, attribution touch, list_ads item), which the schema's terse 'One of the agent's ads' does not convey. agent_id semantics (authorization scoping) are left to the schema, so it is not a full 5.

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?

Names a specific verb (get) and resource (one Meta ad) and enumerates the concrete fields returned: title, media, catalog product, and attribution rollups (taps by channel, private replies, conversations/contacts/leads). It also situates the tool against the sibling list_ads by naming it as a source of ids, so an agent can tell get from list without opening schemas.

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 tells the agent where a valid ad_id comes from — a conversation's latest_ad_id, the ad.id of an attribution touch, or an item of list_ads — which is exactly the context needed to invoke it. It stops short of an explicit when-not-to-use statement or a direct contrast with list_ads for enumeration, so it is strong but not complete.

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