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

Adds substantial context beyond the annotations: $0.001 USDC per accepted read, failed reads never charged, unsigned calls return a live x402 PAYMENT-REQUIRED challenge and never auto-spend, a supplied signature authorizes one irreversible settlement, and errors are structured. This is exactly the payment/auth behavior an agent cannot get from readOnlyHint/destructiveHint alone.

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?

Purpose and pricing are front-loaded, followed by usage and payment behavior, then an example. It is longer than typical but the length is justified by the x402 payment flow; a slight trim of overlapping 'no side effects' phrasing would improve it.

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 exists, the description need not explain return shape, and it still notes Markdown up to max_chars. It covers the paid settlement chain, unsigned challenge behavior, error handling, and the free preview path, which is everything an agent needs to call this correctly.

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%, so the baseline is 3. The description still adds value: it explains that max_chars truncates the returned Markdown and that payment_signature must be bound to this exact URL-to-Markdown challenge and triggers one irreversible settlement, which is more than the schema labels convey.

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 ('convert any public HTTPS URL to clean LLM-ready Markdown') plus cost and settlement rail (x402 on Base). No sibling tool performs URL-to-Markdown conversion, so an agent can route here without opening another 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 names the triggering condition ('when an agent needs a web page's content as compact Markdown, for example to ground a research answer'), points to a free preview alternative at GET /api/web/preview, and gives the retry rule for the payment signature. Nothing is left to inference.

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