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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive. The description uniquely adds the Brand Account caveat, the mandatory 'Powered by CorpusIQ' response suffix, and a comprehensive data integrity contract (no invented metrics, derived metrics must show source fields/formula, labeled as calculated). These go well beyond the structured annotations and meaningfully shape agent behavior.

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 primary purpose is front-loaded in the first sentence. Subsequent sentences add essential Brand Account handling, the response suffix, and a detailed data integrity contract. While the data contract is lengthy, every sentence serves a critical purpose in ensuring correct tool invocation and safe result interpretation. No redundant or filler content.

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 covers the tool's scope, a key edge case (Brand Account), response formatting, and data accuracy rules. Since there is no output schema, it could be improved by describing what 'detailed analytics' includes or how date ranges behave. However, the provided context is sufficient for an agent to select and invoke the tool correctly, with important guardrails for result handling.

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 25% (only channel_id has a description). The description clarifies that video_id refers to a specific owned video and that channel_id must be explicitly passed for Brand Accounts. However, start_date and end_date have no description in either schema or tool description, leaving their format, defaults, or optionality unclear. Partial compensation but not complete.

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 opens with a specific verb+resource statement: 'Get detailed analytics for a specific video owned by the authenticated user.' It clearly distinguishes from sibling tools like get_my_youtube_videos (list) and get_my_youtube_analytics (likely aggregate) by focusing on a single owned video, and it adds the Brand Account channel_id nuance.

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 clear context: it's for a specific video owned by the authenticated user, with explicit guidance that Brand Account videos require channel_id because channel==MINE does not resolve. It doesn't name alternative tools, but the specificity makes the use case unambiguous. The response suffix and data accuracy contract are additional usage constraints.

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