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 fully covered by structured data. The description adds nothing beyond that: no mention of quota/rate limits, result ordering, or pagination behavior. The one useful addition (accepted channel identifier formats) is really parameter semantics, not behavior.

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, no filler: the capability and scope come first, the input-format clarification and intent example follow. Every clause earns its place.

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?

An output schema exists, so return values need not be explained, and the annotations cover safety. However, for a search tool the description omits result-count/limit behavior and any routing hint versus its three sibling search/list tools, leaving the agent to guess on the main selection ambiguity.

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 0%, so the description carries the burden. It usefully documents that 'channel' accepts an id, @handle, or URL — the genuinely ambiguous input — but says nothing about 'query' semantics (full-text? channel-scoped?) or what 'limit' controls. Partial compensation for a total schema gap.

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 and resource ('search for videos') with a tight scope qualifier ('inside one YouTube channel by keyword'), plus a natural-language restatement of the intent. This scope cleanly separates it from search_youtube (all of YouTube) and get_channel_videos (unfiltered listing), so an agent can select it without opening the 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?

The example phrase 'find the video where <channel> talks about <topic>' implies the intended scenario well, but the description never states when to prefer this over search_youtube or get_channel_videos, nor any exclusions or prerequisites. Usage is inferable rather than stated.

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