validate_url

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

No annotations are provided, so the description carries the full burden. It discloses the supported platforms and local file paths, which is useful context. However, it does not mention the return format, what happens for unsupported URLs, or any validation side effects. The output schema likely covers return values, but more behavioral detail (e.g., 'this is a read-only check') would improve clarity.

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 concise, with exactly two sentences: first stating the purpose, second listing supported inputs. It is front-loaded and every word earns its place with no filler or redundant information.

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 single-parameter validation tool with an output schema, the description is largely complete: it states the purpose, enumerates supported platforms, and notes local paths. It does not explain what the output will look like, but the output schema can handle that. It could mention error/unsupported behavior, but that is a minor gap given the tool's simplicity.

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 contains only a bare 'url' field with no description (0% schema coverage). The description compensates by clarifying that the parameter accepts URLs from the listed platforms plus local file paths, implying the accepted format. It adds significant meaning beyond the schema, though it could be more explicit about expected URL formats (e.g., with or without protocol).

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 explicitly states the tool determines the platform and support status of a video link, and lists all supported platforms (bilibili, youtube, douyin, tiktok, kuaishou, local file paths). This is a specific verb+resource with clear scope and distinguishes it from all sibling tools, which focus on tasks, providers, and transcriber models.

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?

Usage is implied: any video URL can be passed to check its platform and support. The description does not explicitly say when to use this tool versus alternatives, but sibling tools have no overlap, so no exclusions are necessary. The lack of explicit scenario guidance (e.g., 'use before downloading') makes it adequate but not proactive.

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