browser_download

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

With no annotations, the description carries the full burden and does a good job exposing non-obvious behavior: it requires yt-dlp, returns install instructions instead of failing silently if it is missing, and never performs silent installs. It does not describe return values or file effects, but the most surprising behavioral traits are disclosed.

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 two efficient sentences: the primary action is front-loaded and the dependency caveat follows immediately. There is no filler, duplication of schema fields, or 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?

Given three parameters, no annotations, and no output schema, the description covers the main invocation concern: the external dependency and what happens when it is absent. It does not specify the return value or the download destination, but an agent can still select and call the tool correctly from the schema plus this context.

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% and each parameter already has clear descriptions and enums. The description adds little semantic value beyond restating the artifact types that already appear in the format enum, so the baseline score of 3 is appropriate.

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 names a specific verb and resource: 'Download media from a URL' with the artifact types enumerated (video, audio, subtitles, thumbnail). This clearly differentiates it from the sibling browser_* tools that deal with navigation, clicking, screenshots, or page content.

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 intended use is implied clearly: use this when you need to download media from a URL. However, it does not explicitly say when to prefer this tool over a sibling or when not to use it, and the yt-dlp requirement reads as a prerequisite rather than comparative usage routing.

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