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

Goes well beyond readOnlyHint/openWorldHint: pricing ($0.002 USDC per successful call via x402 on Base, Solana or Arc), that failed calls are not charged, that a down site returns a valid 200 with up=false rather than an error, and the redirect/TLS/content-type output shape. These are exactly the non-obvious traits an agent needs before paying for a call.

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?

One dense paragraph, front-loaded with the verb, scope and output list, then behavior and price. Every sentence carries information, though the output-field enumeration could be trimmed since an output schema exists.

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 an output schema, the description need not explain return values but volunteers the down-site semantics anyway. Combined with pricing, redirect cap and per-hop measurement, nothing material is missing for correct invocation.

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 coverage is 100% and the schema already states the comma-separated 1-to-5 URL constraint, so the description mostly restates it. It does add value by tying the five-URL cap to the per-call price model, which clarifies the cost of a multi-URL call.

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 and resource ('Checks up to five public URLs now from this Worker') and immediately enumerates the returned facts, so the agent knows exactly what operation this is. It is clearly separable from siblings like pagespeed, headers, ssl or redirects by its liveness-check focus.

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 'now' and 'one GET per hop, so it measures the first response, not the full page' clauses implicitly route full-page-performance needs to pagespeed, and the five-URL cap is stated. There is no explicit when-not statement or named alternative, so it stops short of a 5.

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