youtube_transcript

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

With no annotations, the description fully discloses behavior: default returns whole transcript, window edges return whole caption lines, language fallback order, presence of language and auto_generated fields, absence of timestamps, and the Shorts limitation. This is rich, actionable behavioral context.

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 well structured with a clear lead sentence followed by logically grouped details. Every sentence adds value—parameters, language behavior, output characteristics, and a pointer to an alternative—without unnecessary fluff.

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 tool with 3 parameters, an output schema, and no annotations, the description covers all critical aspects: input URL format, parameter semantics, edge cases, language handling, output limitations, and unsupported cases. It is fully complete for an agent to select and invoke correctly.

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%, but the description adds semantic nuance beyond schema: it clarifies that start_seconds/end_seconds narrow the response, that 'the whole thing' is returned by default, and that caption lines straddling the window are returned whole. This goes beyond the schema's terse descriptions.

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 opens with a clear, specific verb and resource: 'Read what is said in a YouTube video, as plain text.' It also differentiates from siblings by explicitly naming youtube_video_facts for metadata-only needs, making the tool's scope unmistakable.

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?

It provides explicit usage guidance: use start_seconds/end_seconds for long videos to keep responses small, warns that Shorts are unsupported, and directs users to youtube_video_facts when they only need title/length/view count. This covers when, when-not, and alternatives.

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