List supported sites

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

The description adds a useful caveat that extractor names indicate potential support, not a permanent compatibility guarantee. The readOnlyHint annotation already signals no side effects, and the description adds relevant behavioral nuance beyond that.

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 brief, direct, and front-loaded with the core action and resource. Every clause earns its place, including the caveat about compatibility, without unnecessary detail.

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 listing tool, the description gives enough context: what is returned (extractor names), what the input controls (limit and query), and an important caveat about support durability. No output schema is provided, but the return value is clear from the description.

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 already describes both parameters: limit and query. The description does not add much beyond the schema, though it does align 'search' with the query parameter and 'list' with the overall purpose, keeping semantics clear.

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?

Clearly states the action ('list or search') and resource ('extractor names provided by the locally installed yt-dlp version'). This distinguishes it from sibling tools like inspect_media and download_media, which perform different actions.

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 implies when to use the tool—when you need to know which extractors are available—but does not explicitly contrast it with alternatives or state when not to use it. Usage is inferable from the sibling tool names, but not directly stated.

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