get_creative_performance

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

With no annotations, the description carries the full behavioral burden. It does clearly signal a read operation ('Retrieves') and lists the categories of data returned, but it does not disclose scoping behavior, defaults, or limitations such as what happens when no campaignIds/creativeIds are provided or whether results are sorted/aggregated. This is adequate but leaves gaps.

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 compact and front-loaded, with the core 'what' in the first sentence and metric detail in the second. The final sentence ('Essential for creative optimization') is slightly promotional but provides useful context and does not harm readability.

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?

Given a 7-parameter tool with no output schema and no annotations, the description is serviceable but incomplete: it does not describe the response shape, time-series behavior, or default scoping when filters are omitted. The 100% schema coverage compensates for parameter meaning, but the lack of an output schema means more behavioral context would be valuable.

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 100%, so the baseline is 3 and the schema already documents all seven parameters. The description adds context around output metrics (e.g., video metrics, dwell time) that hints at includeVideoMetrics, but it does not explain parameter syntax, defaults, or filtering semantics beyond the schema.

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 opens with a specific verb and resource: 'Retrieves performance metrics for individual ad creatives.' It names concrete metric categories (engagement, video, dwell time) and the intended use, and the 'individual ad creatives' framing distinguishes it from sibling tools like get_campaign_performance, which operate at campaign level.

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?

'Essential for creative optimization' signals a use case but does not explicitly state when to choose this tool over siblings such as get_campaign_performance, compare_performance, or get_conversion_performance. There is no when-not guidance or mention of alternatives, so the agent has to infer the boundary from the tool name and the phrase 'individual ad creatives.'

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