Audience Insights

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

Annotations already declare readOnlyHint, destructiveHint, idempotentHint, and openWorldHint. The description adds that input can be omitted for all platforms and provides the exact return fields, going beyond annotations. No contradictions.

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?

Description is three sentences: first states purpose, second explains input, third says when to use. Every sentence earns its place with no redundancy. Front-loaded with purpose.

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 2 parameters with full schema coverage, no nested objects, no output schema, and annotations covering behavior, the description is complete. It lists all return fields. Only minor gap: not mentioning return type or format (e.g., if it returns a JSON object). Still very good.

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 baseline is 3. Description adds meaning by explaining optionality ('optional — omit for all platforms') and scoping behavior ('scope to a single campaign'), which is not in schema descriptions. This adds value beyond schema.

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 the tool provides demographic and behavioral breakdowns of ad audiences. It uses specific resources: 'demographic and behavioural breakdown' and 'audiences served by your ads'. This distinguishes it from siblings like 'ads_report' or 'competitor_benchmark'.

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?

Explicitly states when to use it: 'Use when refining targeting or reporting audience coverage'. While it doesn't explicitly mention when not to use it or alternatives, the context is clear enough.

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