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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description earns credit for adding genuinely new operational context: a per-call price of $0.005, a free sample payload, and a live (not cached) execution model. It omits auth requirements and error/timeout behavior, so it is strong but not exhaustive.

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?

Three dense sentences, front-loaded with what the tool measures, then price, then a copy-pasteable sample, then the return shape. No sentence is filler; the terse field list is efficient rather than sloppy.

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?

With no output schema, the description carries return-value disclosure itself and does so by naming the keying (by URL) and the entry fields (ok, code, ms, dns_ms, ip, ttl, ns, cert_days, server, ts), plus cost and an example call. Missing only edge-case behavior (failures, redirects, rate limits) for a tool with a cost and network dependency.

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% with a single 'sites' array parameter, so the baseline is 3. The description marginally helps by saying 'one or more URLs' and providing a literal sample ('{"sites": ["https://example.com"]}'), but it omits the schema's maxItems=10 cap, adding little beyond the schema.

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?

States a specific verb+resource combination — a live check of one or more URLs — and enumerates the concrete measurements returned (HTTP status, latency, DNS resolve time, resolved IP, TTL, nameservers, TLS days). It overlaps substantively with siblings like domain_dns, domain_tls and page_watch but never names or distinguishes itself from them, so it stops short of a 5.

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 word 'Live' implies the tool is for real-time rather than cached/historical checks, and the per-call price signals a cost-consciousness framing, but there is no explicit when-to-use statement and no named alternative (e.g. domain_dns, page_watch) for the closely related checks. Usage is implied rather than stated.

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