Audience Demographics

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

Annotations already declare readOnly, destructive, idempotent, openWorld hints. Description adds useful behavioral context: returns percentage data, indicates that empty rows may occur if viewership data is insufficient, and explains error 403 requires re-authentication. This is extra value beyond 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?

Well-structured with clear sections: purpose, Args, Returns, Examples, Errors. Front-loaded with the main functionality. Each sentence adds necessary information; no fluff. Efficiently covers all needed aspects in a readable format.

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?

Despite lacking an output schema, the description includes a full JSON shape of the return value, covering columns and example rows. Handles date ranges, optional parameters, default behavior, and common errors. Sufficient for an agent to understand and invoke the tool correctly.

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 coverage is 100%, so baseline is 3. Description adds value by providing return shape (JSON with columns/rows), default values, and examples showing parameter usage. It clarifies the meaning of dates and the response_format enum. Slightly redundant with schema but still helpful.

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?

Clearly states the tool retrieves age group and gender distribution of viewers as percentages. Specific verb 'retrieve' and resource 'age and gender distribution' with no ambiguity. Distinguishes itself from sibling analytics tools like youtube_revenue and youtube_traffic_sources.

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?

Provides example calls with and without arguments, and describes error scenarios. However, no explicit guidance on when to prefer this tool over siblings. The examples implicitly guide usage for date ranges, but lacks 'when not to use' or alternatives.

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