check_link

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful behavioral detail by listing the returned metrics, which matters because there is no output schema. However, it does not mention redirects, timeouts, or that a live network request occurs, so some behavioral ambiguity remains.

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?

A single, front-loaded sentence conveys the core action and the most important output fields without wasted words. Every element earns its place.

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 low-complexity tool with one parameter and read-only annotations, the description is largely sufficient: it states the purpose and the return fields despite the absence of an output schema. It loses a point because the large sibling group contains several overlapping tools, and the description does not proactively disambiguate them.

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 single required parameter 'url' has 100% schema description coverage with an example. The tool description adds no additional parameter semantics, but because the schema already documents the parameter well, 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 states a clear verb and resource ('check if a URL is reachable') and enumerates concrete returned fields (HTTP status code, response time, content type, SSL status). This distinguishes it from similar siblings like validate_url or check_ssl, though it does not name those alternatives explicitly.

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?

No guidance is given for when to use this tool versus closely related siblings such as check_ssl, check_headers, validate_url, or check_performance. The intended use case is implied but never stated as a choice rule, and no exclusions or alternatives are mentioned.

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