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

Annotations only cover read-only/open-world safety; the description adds the behavioral context that matters here: quota exhaustion behavior, exact pricing, the x402 payment flow with header names (X-PAYMENT/PAYMENT-SIGNATURE), and the explicit 'no account is created' note.

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-loads the key qualifiers (FREE, no key, quota) and is dense with useful facts, but the x402/EIP-3009 payment walkthrough is heavy for a description and could be trimmed or deferred to a link.

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, yet the description still names the response fields (results, quota, report) so an agent knows what comes back alongside the cited-brief upsell. Nothing needed to select or invoke the tool is missing.

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 parameters are already documented; the description reinforces the k cap ('up to 5 results each') and the live-web nature of the query, adding modest value over the schema without introducing new syntax.

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 ('LIVE web search') and immediately distinguishes itself from the sibling `search` by scope ('the open web, not the published corpus'). An agent can choose between web.search and search 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 about when to use this vs `search`, describes the free tier limits (25 queries/day, 5 results each), and gives a concrete escalation path (paid leg at $0.02, or the report brief) when raw results are insufficient.

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