list_user_subscriptions

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

With no annotations provided, the description carries the full burden of disclosing behavior. It clearly states retrieval (read-only) and explains pagination via max_results and page_token, and part selection, which are behavioral traits. It does not detail authentication scopes or quota limits, but the 'authenticated user' phrase implies auth requirements. This is more transparent than a minimal description.

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?

The description is well-structured with a clear purpose statement, an Args section listing each parameter with defaults and valid options, and a Returns section. Every sentence earns its place; it is concise yet complete, covering all necessary information without fluff.

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?

The description fully specifies the tool's function, parameters, defaults, and return format. Since an output schema exists, it need not detail return fields beyond the summary provided ('data', 'error', 'successful'). For a list operation of this complexity, the description is complete and self-sufficient.

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 input schema provides only types and defaults with zero description coverage. The description compensates thoroughly by explaining each parameter: max_results (range 0-50, default 5), page_token (from previous response), and part (valid values and default). This adds substantial meaning beyond the raw 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?

The description clearly states the tool's action and target: 'Retrieves the authenticated user's YouTube channel subscriptions.' This specific verb+resource combination distinguishes it from sibling tools such as list_user_playlists or list_channel_videos, leaving no ambiguity about its function.

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 description provides clear context: it is for retrieving the authenticated user's subscriptions with optional pagination and part selection. It does not explicitly mention when to avoid using it or provide alternative tool references, but the intended use case is evident. This aligns with 'clear context, no exclusions'.

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