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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), but the description adds substantial context beyond them: partial-success semantics with a `failed` list and per-URL reason, the no-charge guarantee when every URL fails, and the billing/auth model (x402 on Base, prepaid x-credit-token header, no free tier, no API key). That is exactly the kind of operational detail an agent cannot infer from structured fields.

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?

Densely front-loaded: the batch scope and JS capability lead, followed by the failure model, then the pricing/routing caveats. Every sentence carries information, though the payment-model detail (x402, prepaid header, no free tier) is somewhat compressed into a single trailing clause.

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?

An output schema exists so return values needn't be spelled out, yet the description still explains the partial-failure shape. Combined with the routing guidance, billing model, and required-input note, an agent has everything needed to call this correctly on the first attempt.

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?

Only one parameter with 100% schema description coverage ('URLs (comma-separated, max 5)'), so the schema already does the work. The description repeats the comma-separated/max-5 constraint and labels the input required, adding emphasis but no new meaning. Baseline 3 is appropriate.

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 with scope: 'Up to 5 pages in one call', 'Pass up to 5 URLs (comma-separated) and get each page back as clean text with its title.' It also distinguishes itself from the sibling url-extract by name, so an agent can route between them without opening either 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?

Explicit when-to-use ('Renders pages that build their content in the browser... covers the SPAs, dashboards and app pages that url-extract deliberately refuses') and when-not ('For a single static page, url-extract is cheaper'). Both the alternative and the selecting condition are named.

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