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

Annotations already indicate read-only and non-destructive, but the description adds significant behavioral details: requires an API key, charges 1 credit per transcript retrieved including repeat calls, skips videos without captions, provides a cost estimate, and specifies rate limits. These are valuable beyond the structured annotations.

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 efficiently front-loaded with the main action and output format, followed by usage context, cost, and rate limit. Every sentence contributes unique information with no redundancy or fluff. It is appropriately sized for the tool's complexity.

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?

Given the simple schema (2 params) and existing output schema, the description covers all necessary angles: purpose, ordering, output format, usage contexts, alternative tools, cost behavior, rate limits, and authentication. It is fully complete for an agent to select and 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?

Schema coverage is 100% for both 'url' and 'limit', so the baseline is 3. The description adds practical context for the 'limit' parameter by explaining the credit charge per video and advising 'start with a small limit', which meaningfully enhances understanding of cost implications. This exceeds the schema's pure definitional coverage.

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 uses a specific verb ('Get transcripts') with a clear resource ('videos in a YouTube playlist') and output format ('timestamped markdown, one section per video'). It explicitly distinguishes itself from sibling tool get_transcript for single videos. This is unambiguous and well-differentiated.

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?

Provides explicit when-to-use guidance: 'Use for working through a course, series, or curated list' and directly names the alternative for single videos: 'for one known video use get_transcript'. This clearly communicates appropriate contexts and exclusions.

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