List custom audiences

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful output-composition context (size, targetable status) and the targeting use of the IDs, but does not mention pagination behavior or limits. This is acceptable but not rich beyond the annotations.

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?

Two compact sentences with no filler: the core action is front-loaded, and the second sentence adds a genuinely useful post-call usage note. Every word earns its place.

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 simple read-only list tool with one required parameter and strong annotations, the description covers purpose, output content, and downstream usage. Minor gaps remain: it never explains what 'targetable status' means or that cursor/count drive pagination, but these are not blockers for a tool of this complexity.

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 33%: count and cursor are completely undocumented, and the description does nothing to compensate (no mention of pagination or count semantics). It clarifies the meaning of the returned audience IDs, but that is output semantics, not parameter meaning.

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 a specific verb and resource ('List tailored audiences') and adds output details ('with size and targetable status'), so an agent knows exactly what the tool returns. The downstream note ('Use ids as CUSTOM_AUDIENCE targeting values') further separates it from audience-management siblings like create/update/delete and from list_targeting/list_creatives.

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 'Use ids as CUSTOM_AUDIENCE targeting values' sentence implies this is the tool to fetch audience IDs for targeting, which is useful but indirect. There is no explicit when-to-use/when-not-to-use guidance against adjacent siblings such as x_ads_list_targeting, x_ads_audience_users, or x_ads_audience_targeted.

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