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

Annotations already establish readOnlyHint=true and destructiveHint=false. The description adds valuable behavioral context beyond those annotations, notably that the request is metered/cost-sensitive and that output granularity depends on include_segments and video_count, making the tool's behavior more predictable.

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?

The description is tightly structured: the first sentence states the action and resource, the second lists the primary configurable dimensions, and the final warning ('metered batch request') is useful caution with no fluff. Every sentence 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?

The description is adequate for a read-only batch tool with an output schema and clear annotations, covering the key decision dimensions and metering behavior. What is missing is an explicit pointer to the single-video transcript sibling tool for non-batch needs, though 'batch' in the name and description make this reasonably inferable.

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?

With only 20% schema description coverage, the description carries the burden for the other parameters. It maps 'video count,' 'ordering,' 'language,' and 'timestamped segments' respectively to video_limit, sort_by, language, and include_segments. It does not restate concrete values, but those are already captured by enum/default/constraint in the 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 description states a specific verb ('Fetch'), a clear resource (YouTube channel transcripts), and narrows the scope to a 'selected batch of videos,' which distinguishes it from single-video transcript tools like get_youtube_video_transcript and channel metadata tools like get_youtube_channel.

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 description implies batch usage with 'selected batch' and notes it is a 'metered batch request,' but it does not explicitly mention alternatives or when-not-to-use conditions. An agent can infer the intended use case from the batch wording, but the routing is not made explicit.

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