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

Annotations only cover the safety profile (readOnly, non-destructive, open-world, non-idempotent); the description adds materially more: the exact price and chain/rail ($0.005 USDC on Base via x402), that the page is fetched at call time, and the full enumeration of return statuses plus similarity/context/sha256. This is behavior an agent cannot derive from the annotations or schema.

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?

Three tight sentences, no filler, and the critical call-without-payment instruction is placed last where it is easy to act on. Slightly off-balance in that pricing leads ahead of the tool's actual purpose.

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?

With no output schema, the description does the necessary work of enumerating return fields, and the payment path is explained. Minor gaps remain: matching semantics for the quote and whether payment is charged per call or only on success.

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 description coverage is 33% – only `payment` is documented, and the description merely restates the payment handshake that the schema already explains. The required `url` and `quote` parameters get no added semantics (matching mode, normalization, length limits, or error behavior), so the description does not compensate for the coverage gap.

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+resource: fetches the live page and verifies whether a given quote is present, naming the exact result vocabulary (found_exact/found_near/partial/not_found/page_unavailable). No sibling (read_page, preview_page, check_links) does quote verification, so the tool is trivially distinguishable.

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?

"Call without payment to get the x402 requirements" gives concrete invocation sequencing for the paid handshake, which is the main usage trap here. It does not, however, state when to prefer this over read_page/preview_page or any exclusions.

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