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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavior beyond annotations: the 0.0001 XNO charge via x402, the redirect-chain and TLS-detail scope, and the previous_hash body-comparison mechanism. No contradiction with the annotations is present.

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 a single, information-dense sentence with no filler. It front-loads the tool's identity, lists the key result dimensions, and ends with the cost detail; every phrase 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?

Given the output schema exists and annotations cover safety, the description is largely complete: it explains scope, cost, and the previous_hash parameter. The main gap is the absence of guidance for choosing this tool over sibling URL-related tools, but that is not essential for understanding the tool's own behavior.

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 description coverage is 100%, so the baseline is 3. The description adds a small amount of semantic context by explaining that previous_hash is passed to detect body changes, but it does not add new format, algorithm, or usage details beyond what the schema already provides.

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 resource ('URL') and the action ('status check'), then specifies the exact outputs: final HTTP status, redirect chain, TLS validity, response time, and body change. It does not explicitly differentiate from the sibling tool check_link, but the detail and 'one-call' framing give enough distinctiveness.

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 provides no guidance about when to choose this tool over siblings like check_link, domain_info, or extract_url, and no when-not-to-use conditions. It implies comprehensive URL checking via its feature list, but that is not enough to route an agent to the correct tool.

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