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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds non-obvious behavior: pagination size (50 at a time), sort order (by views), and a licensing gate on one class of data. It doesn't state what happens when a page boundary is hit, but the added context is solid.

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?

Two sentences, zero filler, with the core capability front-loaded and the licensing caveat second. Every clause carries information an agent needs.

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 simple read tool with no output schema, the description covers scope, paging, sorting and feature gating, which is nearly everything needed. The one gap is that neither parameter is required, so it never says that an id or handle must actually be supplied to get a result.

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%, and the schema already explains that id is used 'if no handle' and handle is the @channel form. The description adds no parameter-level detail, so the baseline 3 applies when the schema does all the work.

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 states a specific resource and scope: every upload on a YouTube channel, paginated 50 at a time, sorted by views. That is far more specific than the name alone. It does not name how it differs from siblings like video_check or video_site, so it stops short of a 5.

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?

It draws a useful boundary by saying the per-check tally requires a Watch licence 'and is not offered here,' which tells the agent not to expect that data. However, there is no explicit when-to-use guidance or named alternative for retrieving channel-level versus site-level video data.

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