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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds one piece of behavioral context — the output is recorded evidence, not inferred spend/performance — which is a meaningful limitation but the only disclosure beyond the annotations.

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 tight sentences: the action is front-loaded and the negation about inferred metrics immediately follows. No filler or redundancy.

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, the description should convey what 'recorded evidence' looks like when returned (fields, per-ad structure, how the two-to-four ads are presented), and it does not. Annotations carry the safety story, so this is adequate but leaves the return shape unspecified for a comparison tool.

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 description coverage is 0% and the single parameter is an array of ad objects whose platform enum and id constraints are undocumented. 'Two to four' merely restates minItems/maxItems, and only the word 'distinct' adds meaning not in the schema, so the description does not compensate for the coverage gap.

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 ('Return recorded evidence') plus the scope ('two to four distinct ads for comparison'), so the comparison intent is clear. It does not, however, explicitly differentiate itself from get_ad_evidence or search_ads, which a single clause could have done.

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?

The line 'does not infer competitor spend or performance' usefully bounds what the tool will not do, but there is no guidance on when to pick this over get_ad_evidence or search_ads, nor any prerequisite about the ads needing to already exist.

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