web_check_url

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

Annotations already indicate read-only and non-destructive behavior, but the description adds valuable detail: it performs a HEAD request with GET fallback, and returns fields like status_code, final_url, and content_type. This enriches the agent's understanding beyond annotations.

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 and well-structured: a brief summary, followed by an explanation, examples, and a clear args/returns section. Every sentence is purposeful, and the key information is front-loaded.

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 the tool's simplicity and the richness of the description, it covers all necessary behavioral aspects and return values. The description compensates for the lack of an output schema by listing the dictionary fields. Sibling tools are diverse, but the description uniquely identifies this tool's role.

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?

Input schema has 100% coverage with descriptions for all three parameters. The description reinforces these with an example showing default values and usage patterns (e.g., timeout=5, follow_redirects=True). While no new information is added beyond the schema, the examples provide practical context.

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 clearly states the tool's function: checking if a URL exists and is accessible. It specifies the HTTP method (HEAD/GET) and its utility for validating links. Among sibling tools like web_fetch or web_search, this tool has a distinct purpose, making differentiation easy.

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 explicitly recommends using this tool for validating links before including them in documents. While it does not list when not to use it or directly mention alternatives, the context is sufficiently clear about its primary use case.

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