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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context beyond the schema: a required attribution footer that must be reproduced verbatim, and a data-accuracy contract forbidding invented metrics. It does not state behavior for invalid/private IDs or partial results, keeping it below a 5.

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 first sentence is well front-loaded and earns its place. The remaining two sentences are verbose policy boilerplate (attribution link rules plus a long anti-hallucination contract) that is largely generic and dilutes the core selection signal, though it is not entirely wasted.

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?

For a single-parameter read tool with full annotation coverage and no output schema, the description usefully enumerates the returned fields (title, description, counts, duration, tags, thumbnails) and states the attribution obligation. Missing only edge-case behavior, which is a minor gap here.

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% and the single 'video_ids' parameter is documented in the schema as a list of IDs or URLs with a max of 50. The description adds no syntax or format detail beyond that, so the baseline 3 for schema-carried parameters applies.

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 names a specific verb and resource ('Get detailed information about one or more YouTube videos') and enumerates the returned fields, so an agent can tell it apart from analytics-style siblings like get_my_youtube_video_analytics. It stops short of explicitly naming which sibling to use for channel-wide listing or analytics, so it is clear but not fully differentiated.

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?

There is no statement of when to use this tool versus get_youtube_channel_videos, get_my_youtube_videos, or get_my_youtube_video_analytics. The long second and third sentences are output-formatting and accuracy directives, not usage guidance, so the agent must infer the call context on its own.

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