YouTube transcript

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds genuinely useful non-annotation context — the 1-credit cost with refunds on failure — and enumerates the return fields, but says nothing about failure modes such as videos lacking captions or rate limits. The cost disclosure is the strongest addition and lifts it above baseline.

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?

Front-loaded with the purpose, then two compact labeled lines for cost/input and returns; no filler prose. Minor waste in restating 'Provide one of: url OR id', which duplicates the schema description verbatim, but overall it is tight and scannable.

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?

With no output schema, the explicit return-field enumeration (video_id, language, is_auto_generated, available_languages, text, segments) is a real contribution, and the cost line covers billing expectations. However, for a tool whose practical failure mode is 'no captions exist', the absence of any note on missing/auto-generated caption fallback leaves a meaningful behavioral 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?

Schema description coverage is 100%, so id, url and lang are fully documented in the schema itself, including examples and defaulting behavior. The description only echoes the one-of constraint and alludes to language selection through the return fields; it adds no syntax or format detail beyond the schema. Baseline 3 applies.

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?

States a specific resource (YouTube video transcript from captions) plus the exact shape of what comes back: timed segments, joined plain text, chosen language, and available caption languages. That makes it trivially distinguishable from siblings like youtube_video (metadata) and tiktok_transcript (different platform) without opening a 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?

Contains no when-to-use or when-not-to-use guidance relative to alternatives; the only directive is the input constraint 'Provide one of: url OR id', which merely restates the schema's own description. Nothing tells the agent when to prefer this over youtube_video, or what to do when captions are unavailable.

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