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

With no annotations, the description carries the full burden. It usefully discloses cost (1 credit), ordering behavior, and accepted playlist formats. However, it claims to list 'every video' while the schema's limit parameter has a default of 100 and a max of 1000, with no clarification about pagination or whether the limit must be raised to see all videos. Return-value shape is also not described.

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 four short sentences, each earning its place: purpose and ordering, input format, cost, and a high-value usage tip. It is front-loaded with the core action and contains no filler or redundant restatements of the title.

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 2-parameter read tool, it covers purpose, input, cost, and use-case. But the unresolved tension between 'every video' and the limit parameter, plus no information about the response format or pagination, leaves meaningful gaps. Given there is no output schema or annotations to fill those gaps, the description alone is not fully complete.

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 the schema already documents both parameters well. The description's 'playlist URL or bare playlist id' essentially mirrors the schema's 'Playlist URL or id (the list= value)' without adding significant new meaning. The chain-to-transcripts tip is workflow guidance, not parameter semantics.

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 specific verb and resource: 'List every video in a YouTube playlist,' and adds a distinctive trait (playlist order) that separates it from the sibling channel/search/latest tools. The title reinforces this clearly, and the input-form detail (URL or bare id) leaves no ambiguity about scope.

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 gives clear contextual guidance: playlist order is preserved for courses/series, and it recommends chaining into get_transcripts for bulk extraction. It doesn't explicitly state when not to use it versus siblings like get_channel_videos, but the context is strong enough for an agent to select it appropriately.

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