get_adgroup_performance

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

No annotations are provided, so the description must convey behavioral traits. It only states that the tool is a 'read' operation and a 'stub', but does not disclose data freshness, permissions, rate limits, or whether the tool returns live or historical data. This is insufficient for an agent to anticipate tool behavior.

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 extremely concise with two sentences. Each sentence adds distinct value: the first states the purpose, the second provides a critical caveat about availability. No unnecessary words or repetition.

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 the complexity of the tool (7 optional parameters, no output schema), the description is somewhat sparse. It does not explain what metrics are included in the performance breakdown or how to interpret results. However, the schema fully documents parameters, and the stub nature is clearly stated, providing situational context.

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 input schema already describes all parameters. The description adds no additional meaning or context about the parameters beyond what is in the schema, earning a baseline score of 3.

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?

Description clearly states it provides an 'ad group level performance breakdown', which is a specific verb+resource combination. This distinguishes it from sibling tools like get_campaign_performance or get_keyword_performance by specifying the level of aggregation.

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 notes that it is a 'hosted endpoint only; this local stdio server is an introspection stub', which informs the agent that the tool is not functional locally. However, it does not provide explicit guidance on when to use this tool versus other performance tools, nor does it mention prerequisites or alternatives.

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