List Custom Audiences

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

Annotations already declare readOnlyHint=true and destructiveHint=false; the description's 'Lists' wording is consistent and adds the scope of returned data (audience names, types, size estimates, delivery status). It provides value by enumerating the return payload beyond the annotation, though it does not note pagination cursor lifecycle beyond the after parameter.

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?

Compact and front-loaded with the core purpose; the Args block and return list are functional with minimal filler. Every sentence earns its place, though the response_format omission is a content gap rather than a structure flaw.

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?

With no output schema, the description correctly describes return values. For a list operation of moderate complexity it covers the core flow, but the undocumented response_format parameter means an agent cannot know the output can be markdown or json without inspecting the schema. This is a real but small completeness gap.

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 50% (ad_account_id and response_format documented in schema). The description compensates partially: it explains ad_account_id, limit (range 1–100, default 20), and after (pagination cursor), which adds meaning the schema's bare schema types lack. However, response_format is entirely undocumented in both schema and description, leaving an unresolved parameter.

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?

States a specific verb and resource ('Lists custom audiences in a Meta ad account') and is clearly distinguishable from siblings like meta_list_saved_audiences and meta_list_custom_conversions. A later sentence names the concrete return fields (names, types, size estimates, delivery status), fully grounding what the tool does.

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?

No guidance on when to use this tool versus alternatives. Siblings meta_list_saved_audiences, meta_list_custom_conversions, and meta_get_custom_audience are semantically close, and the description gives no differentiating context or exclusion criteria, so an agent must guess which list tool fits.

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