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

With no annotations provided, the description carries the full behavioral burden and does so well: it discloses the 10-second timeout, Cloudflare edge vantage point, single-request scope, 30-second caching, and the return verdict/reason fields. The 'one vantage point only' warning is especially valuable for interpreting negative results. This is unusually complete behavioral disclosure.

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 definition is front-loaded with the agent's likely question and then efficiently packs timeout, mechanism, return values, and limitations into a compact paragraph. Every phrase adds operational value, and there is no redundant restatement of the name or schema.

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?

Because there is no output schema, the description must explain what comes back, and it does: verdict, reason codes, HTTP status, response time, final URL, and server country/network. It also covers the key limitation of a single vantage point and the 30-second cache. Nothing essential for correct interpretation is missing.

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% for the single url parameter, so the schema already documents the accepted format and example. The description does not add syntax, format constraints, or edge-case handling beyond what the schema provides. The baseline of 3 is therefore 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 opens with the specific question it answers, 'Is a website down?', then names the exact behavior: DNS resolution plus a single URL load. It returns a website availability verdict, which distinguishes it from generic DNS tools like dns_lookup and from service-specific tools like ai_service_status.

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 question framing gives clear context for when to use the tool: checking whether a website is reachable. It also adds the important caveat that results come from one vantage point and are cached for 30 seconds, which helps an agent interpret results. It does not explicitly name when to prefer this over check_dns_propagation or dns_lookup, so it falls short of a full routing guide.

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