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

Beyond annotations, the description adds critical behavioral details: API key requirement, 1-credit cost per call including repeats, advice to reuse transcripts, no cost for videos without captions, and a rate limit of 5 requests per 10 seconds. This enriches the annotation readOnlyHint with concrete operational constraints.

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, each adding essential value: purpose/output, read-only nature, cost/billing, and rate limiting. Front-loaded with the core action, no fluff or repetition.

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 simple one-parameter read-only tool with an output schema, the description covers all necessary behavioral aspects: what it returns, side effects (none destructive), costs, error conditions, and rate limits. Completely sufficient for an agent to invoke confidently.

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?

The schema fully describes the single parameter 'video' with details on ID and URL forms (100% coverage). The description adds 'single YouTube video' scope but no additional syntactic or semantic detail, so it meets the baseline without compensating further.

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 ('Get') and resource ('full transcript of a single YouTube video') with an explicit output format ('timestamped markdown'). It clearly differentiates from sibling tools by emphasizing 'single video', unlike channel/playlist transcript 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?

The description provides clear usage context: read-only, requires API key, charges credits, rate limits, and error behavior. It implies a single-video scope versus siblings, but does not explicitly name alternatives or state when not to use. Solid guidance but not fully explicit about when to choose this over other tools.

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