List targeting

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

The annotations provide readOnlyHint=true and openWorldHint=true, which cover the safety and open-world nature. The description does not contradict these. However, it adds little beyond the annotations: it mentions the tool lists targeting criteria but does not describe pagination behavior, return format, or the exact semantics of the 'groups differ' hint. With annotations covering the safety profile, a 3 is appropriate; it adds some value but not deep behavioral context.

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 concise, at two sentences. It front-loads the core purpose ('List targeting criteria for an ad group') and includes the usage hint in the second sentence. It avoids unnecessary details, though it could be slightly more structured with explicit sections. Overall, it is efficient and focused, with no fluff.

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 tool's complexity (4 parameters, one required, no output schema), the description is reasonably complete for a read-only, open-world listing operation. It provides the key usage hint about line_item_id. However, it does not describe pagination (cursor, count) or the structure of the returned criteria, which might be important for an agent to interpret results. The openWorldHint suggests the output may vary, but without more detail, an agent might be uncertain about handling large result sets or variable schemas.

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 only 25%, with only account_id having a description. The description compensates by explaining the importance of line_item_id, indicating that it affects the returned criteria. This adds meaning beyond the schema, which lacks descriptions for count, cursor, and line_item_id. The description does not explain count or cursor, but the focus on line_item_id is a key semantic addition, making the description valuable despite the low schema coverage.

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 states the purpose clearly: 'List targeting criteria for an ad group', which is a specific verb (list) and resource (targeting criteria). It does not explicitly differentiate from siblings like x_ads_search_targeting or x_ads_add_targeting, but the phrasing 'for an ad group' distinguishes it from broader targeting tools. The hint about line_item_id adds context, but the purpose could be more precise.

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 provides a clear usage hint: 'Always pass line_item_id to see why groups differ.' This tells the agent when to use the tool and why, but it does not mention alternatives or when not to use this tool. The sibling list includes x_ads_search_targeting, which might be an alternative for more specific targeting queries, but no explicit routing is given.

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