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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the exact fields returned per result, the pagination contract ('Pass continuation from a previous response for the next page'), and the negative capability that it does not return spoken content. It stops short of describing result ordering or rate/credit behavior, so it is not exhaustive.

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?

Four sentences, zero waste, and the trigger condition plus examples are front-loaded ahead of the return-value and alternative-tool notes. Every sentence carries distinct information: trigger, return shape, pagination, and boundary with the transcript sibling.

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?

There is no output schema, so the description compensates by enumerating returned fields (title, video ID, link, channel, views, length, upload date) and the pagination mechanism. Combined with annotations covering the safety profile, an agent has everything needed to call this correctly and know what comes back.

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, search_type, and continuation are already documented in the schema, including the note not to construct continuation tokens. The description's mention of passing continuation adds a usage cue but no syntax or format detail beyond the schema. Baseline 3 is correct when the schema does the heavy lifting.

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 verb+resource ('find YouTube videos or channels') with concrete query examples, and explicitly distinguishes itself from the sibling get_youtube_transcript by scope ('Does not return what a video says'). An agent can route between search and transcript without opening either 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?

It gives an explicit trigger condition ('when the user wants to find... before reading or comparing them'), two concrete query examples, and names the alternative tool with the exact condition that selects it (call get_youtube_transcript with a result's video ID). Nothing about when to use or not use this tool is left to inference.

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