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

Annotations already declare readOnlyHint=true, and the description restates 'Read-only', so that adds nothing. However, 'Pro' discloses a plan/subscription gate that annotations do not cover and that affects whether a call succeeds. Beyond that, no error behavior, rate limits, or the consequence of passing both IDs is described.

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?

Three short sentences, front-loaded with the outcome and immediately followed by the inputs. Every sentence contributes a distinct fact (what it returns, what to pass, safety/tier).

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, but the description states the return is preview links, which covers the response shape adequately for a 4-parameter read tool. The remaining gap is the interaction between ad_id and creative_id in the schema's permissive, neither-required setup.

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?

With 50% schema coverage the description carries real weight: it explains ad_id's origin (create_campaign), offers creative_id as an alternative source, and its list of surfaces maps onto ad_formats. It does not clarify whether ad_id and creative_id are mutually exclusive or whether at least one is required, nor does it explain the format enum values beyond the surfaces named.

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?

Specific verb ('Get preview links') plus concrete resource ('how an ad looks on Facebook Feed, Instagram Feed, Stories and Reels'), and it names the exact return artifact. No sibling tool offers previews, so an agent can distinguish it from list_ads or get_creative_library on purpose alone.

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 tells the agent which identifier to supply ('Give an ad_id (e.g. from create_campaign) or a creative_id'), which is real routing guidance between two input paths. It stops short of stating when-not-to-use it or naming alternatives, but the invocation condition is unambiguous.

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