Look up targeting

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

The readOnlyHint annotation already tells the agent this is a safe read, and the description adds nothing beyond that — no information about what is returned, result size, pagination, or whether an ad account/campaign identifier is required. Since annotations cover the safety profile, the description needed to contribute the remaining behavioral context and does not.

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?

A single front-loaded sentence with no repetition or filler. It is appropriately short, though the trailing example list is the only content beyond a restatement of the name, so it sits just below the top of the scale.

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 zero-parameter, read-only lookup the description is nearly adequate, and it does characterize the output categories (interests, locations, audiences). However, with no output schema and no parameter documentation, it should say more about what the lookup returns or what input context (e.g. a campaign) it implicitly relies on.

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 tool takes zero parameters, so the baseline is 4. The description's mention of a 'campaign' scope adds a little interpretive context, but with an empty schema and additionalProperties=true there are no parameter semantics to clarify.

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?

Names a specific verb ('look up') and resource ('targeting options for a campaign') and gives concrete examples (interests, locations, audiences). It is clearly a read operation, but it does not distinguish itself from siblings that also touch targeting, such as create_audience or update_campaign_locations.

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 statement of when to use this tool versus alternatives like create_audience or update_campaign_locations, which appear in the sibling list and overlap in subject matter. The scope 'for a campaign' hints at context but no explicit when/when-not guidance is given.

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