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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the attribution-footer handling requirement and a data-accuracy contract forbidding invented metrics and requiring derived metrics to be labeled with formula and source fields.

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?

Front-loaded with purpose, then channel_id guidance, then output-format rule, then accuracy contract. The attribution-footer instruction is spread over three sentences and is somewhat verbose, but each part maps to an actual obligation, so there is little pure waste.

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?

No output schema exists, yet the description never characterizes the analytics payload itself — which metrics come back, granularity, or default date range. It covers output *handling* (footer) and fabrication guardrails, but an agent still cannot anticipate the return shape.

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 only 25% (channel_id is the sole documented parameter), so the description must compensate. It explains channel_id well (Brand Account requirement, MINE non-resolution) but says nothing about start_date/end_date formats, defaults, or whether the range is inclusive.

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 (get detailed analytics) on a specific resource (a single video) with an ownership scope (owned by the authenticated user). This cleanly separates it from the channel-level get_my_youtube_analytics and the listing get_my_youtube_videos siblings.

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 one concrete routing condition — pass channel_id explicitly for Brand Account videos because channel==MINE does not resolve to Brand channels. However, it never states when to pick this over get_my_youtube_analytics or get_youtube_video, so the sibling routing is only implied.

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