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

No annotations are provided, so the description carries the full behavioral burden. It explicitly says 'Read-only,' defines the scoping boundary, and lists the returned data dimensions. Minor omissions like pagination for 'every creative' or rate-limit behavior prevent a perfect score.

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 two sentences with no filler. It front-loads the action and data scope, then adds the critical scoping/read-only caveat. Every clause contributes information.

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?

There is no output schema, so the description compensates by enumerating the key result groupings and including the read-only, self-scoping constraint. It is near-complete for a zero-parameter read-only endpoint, though details like pagination or exact review-status values are left out.

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?

The schema has zero parameters, and the description adds meaning by clarifying that the call is implicitly scoped to the API key holder and requires no explicit inputs. This is useful context beyond the empty schema, though it stops short of explicitly stating 'no parameters needed.'

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 names a specific verb ('Get') and resource: the advertiser's own 30-day ad performance, including impressions, clicks, breakdowns, and creative review status. It also explicitly distinguishes this tool from reporting on anyone else, which separates it from network or slot-focused 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?

The description clearly states the tool is scoped to the API key holder and cannot report on anyone else, which strongly implies when to use it: for the caller's own stats. It does not explicitly name alternatives or exclusion conditions, but the context is clear enough for an agent to route correctly.

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