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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's job is to add context. It does: results are limited to public videos and are not filtered to Creative Commons, which is a non-obvious licensing trait that affects whether a result is clip-eligible. It says nothing about result count or pagination, keeping it short of 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?

Two sentences, front-loaded with the action, and the second sentence carries only decision-relevant routing and scope information. No filler.

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 one-parameter, annotated, read-only search tool with no output schema, the description covers purpose, routing, and licensing scope adequately. Only the result-shape behavior (how many videos, whether pagination applies) is left unstated, which is a minor gap.

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?

Single parameter with 100% schema description coverage ('Search keywords'), so the schema already carries the meaning. The description's phrase 'keyword search' restates rather than extends the schema, so baseline 3 is appropriate.

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?

Names a specific verb (search) and resource (public YouTube videos) plus the intent behind it (finding a source to clip). None of the siblings perform discovery, so an agent can trivially distinguish this tool from the clip-request and account-management tools.

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?

Explicitly states when to reach for it: 'use this instead of asking the user for a URL when they only have a topic in mind.' It also adds a scope qualifier ('Not restricted to Creative Commons'), giving the agent a boundary condition rather than leaving usage to inference.

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