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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, and the description adds substantial context beyond them: a 5-redirect limit, supported content types, the x402 pricing and payment rails, the guarantee that invalid input is refused pre-payment and failed runs are never charged, and the exact PaymentRequired response when unpaid.

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?

Front-loaded with the core capability and return payload in the first sentence; the rest is dense but each clause carries operational value (limits, pricing, failure semantics, free sample, HTTP equivalent). The trailing example URL is slightly boilerplate but genuinely useful for the paid path.

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?

No output schema exists, yet the description enumerates the returned fields (title, description, language, canonical URL, author, publish date, headings, links, images), so an agent knows what comes back. Payment, failure, and format behavior are all covered for a 3-parameter tool.

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 url, links and max_chars are fully documented in the schema with defaults and ranges. The description adds only indirect hints (Markdown output, redirect handling) rather than meaning beyond the structured fields, so the baseline 3 applies.

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 ('Fetch any public web page') plus the exact output shape ('main content as clean Markdown') and the metadata fields returned. An agent can distinguish this from link_preview or url_safety_check by the payload, though no sibling is named explicitly.

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?

Gives a clear usage context ('Built for agents that need to read or cite the web'), the accepted content types, and an escape hatch for a free sample via get_example. It stops short of explicit when-not-to-use or a direct comparison to the preview/safety siblings.

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