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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, yet the description still adds substantive behavior: a 10-URL batch cap, no JavaScript execution, a $0.003 per-call price with specific payment rails, and a two-call handshake for payment. The only gap is no mention of timeouts, partial-failure behavior when some URLs fail, or rate limits.

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?

Four sentences, each doing distinct work: capability and return shape first, then the sibling exclusion, then cost, then the payment handshake. The important constraints are front-loaded and there is no filler.

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, and the description compensates by naming the returned fields. For a two-parameter batch reader with a non-obvious paid-call protocol, the description covers cost, auth flow, fetch limitations, and the alternative tool — everything needed to invoke it 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?

With 100% schema coverage the baseline is 3, but the description adds real meaning for the `payment` parameter by explaining it is a signed x402 payload obtained by first calling without it — a workflow the schema field alone does not convey. The `urls` parameter is only restated ('up to 10'), not elaborated with format nuances.

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 ('Read up to 10 web pages as clean text in one call') and enumerates the return shape (title, description, readable body, final URL). It also marks itself off from the sibling page_extract, so an agent can route 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?

Gives an explicit when-not condition ('A plain fetch (no JavaScript)') and names the alternative that covers it ('for a rendered page use page_extract'). It also prescribes the exact call sequence for paid use: call once without `payment`, sign, call again with `payment`.

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