List creative-level ad performance

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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so safety is covered. The description adds only a list of output metrics and does not disclose pagination behavior, default windows, rate limits, or how date-range and period parameters interact.

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 a single compact sentence with no wasted text and leads directly with the primary return value. However, terms like 'evidence tiers' and 'modeled remainders' are not clarified, which slightly reduces clarity in such a terse statement.

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 list tool with no output schema, the description gives a high-level indication of returned metrics but does not explain row granularity, pagination, or response structure. The high schema coverage compensates for filter documentation, but an agent still lacks full context on what a response contains.

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 high at 83%, so the schema already documents most parameters in detail, including the from/to versus period conflict and cursor pagination. The description adds no parameter-specific meaning beyond what the schema provides, making the baseline 3 appropriate.

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 clearly states a specific verb and resource: returning ad and ad-set performance metrics including ROAS, CPA, CPC, and related values. It is distinguishable from generic campaign or spend tools, though it does not explicitly differentiate itself from siblings such as list_campaigns or get_spend.

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?

There is no explicit guidance on when to use this tool versus alternatives. The only implied usage is performance reporting, but no conditions, prerequisites, or sibling routing are stated.

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