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

Adds substantial context beyond annotations: it performs one real GET from the tool's server, details which headers contribute to the security grade, states exact pricing ($0.001 per call, 10 free/day, then x402 payment), and explains error returns and charging behavior. Annotations already cover read-only/open-world/idempotent/non-destructive traits, and the description enriches that profile without contradicting it.

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 front-loaded with what the tool returns before moving to usage, pricing, and errors. It packs many details into a dense first sentence, which is efficient but slightly run-on. Overall every sentence adds useful information, with little waste.

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 existing output schema, the description need not explain return values, and it covers the remaining agent needs: scope, alternatives, pricing, and error semantics. For a one-parameter HTTP probing tool with a rich output schema, this is complete enough for correct selection and 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?

There is one parameter and schema description coverage is 100%, so the schema already documents the 'url' input. The description adds no extra syntax or format detail for the URL parameter beyond what the schema provides. Baseline 3 is appropriate when the schema fully handles parameter semantics.

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: probe a site's availability and serving characteristics (status, redirect chain, timings, server, CDN, caching, compression, security headers). It distinguishes itself from sibling web_read by explicitly pointing to web_read for page content. An agent can tell what it does and does not need to open the schema.

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?

Explicitly says 'When to use: For availability, status and timings; for page content use web_read.' This names the condition and the alternative, leaving no ambiguity. It also covers cost and error behavior, giving full invocation context.

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