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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds genuinely new behavioral facts — that the call is free and exactly which fields are returned (IDs, titles, channels, durations, view counts). It omits pagination/limit behavior and any rate-limit notes, 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?

Three tight sentences: scope first, return shape second, cost and next-step routing last. No filler, no repetition of the title, and the most decision-relevant information is front-loaded.

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?

With no output schema, the description usefully enumerates the returned fields and flags the tool as free, which is exactly what an agent needs to chain into get_transcript. Only minor operational details (result ordering, how limit interacts with channel search) are left unstated.

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%, so query, limit, and channel are already fully documented in the schema. The description restates the channel-accepts-link-or-@handle detail that the schema also carries, adding no syntax or format information beyond it. Baseline 3 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?

States a specific verb (search) plus resource (YouTube videos) and additionally defines the channel-scoped variant, which no sibling covers. An agent can distinguish it from get_transcript, list_playlist_videos, and the other siblings without opening any schema.

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?

"Use get_transcript on the videos you need" gives an explicit follow-on routing instruction, and the channel parameter is described as an alternate search mode. It stops short of stating when NOT to use this tool (e.g. versus playlist enumeration), so it is clear context rather than full when/when-not guidance.

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