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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds genuine behavior beyond the annotation: the result set is capped at 50 and ordered newest-first, which matters. It does not say whether the 50 is a hard cap with no pagination or whether older videos are reachable another way — a meaningful omission for a 'newest' list.

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?

A single short noun phrase with no filler, and the most important fact (50 newest) is front-loaded. It loses a point only for being an incomplete sentence that reads like a title restatement rather than a description.

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 zero-parameter, read-only, no-output-schema tool, the definition covers the essentials: what is returned and how many. It is thin on whether the list is paginated, what fields each video carries (IDs? titles?), and whether '50' is a ceiling or a fixed page size — details an agent would want before calling.

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 tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly implies there are no filters (no limit/cursor is offered), which is consistent with the empty 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 fragment names the resource and adds real scope (the account's 50 newest), so an agent can infer a listing of recent videos. But it supplies no verb and never contrasts with the close siblings get_video (single video) or the create/revise/share family, so the definition leans on the tool name to do the work.

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 when-to-use statement, no exclusion, and no alternative named — nothing tells an agent whether to reach for this or get_video when it wants video data. The '50 newest' phrasing only hints at the use case implicitly.

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