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

Far beyond the annotations: it discloses price ($0.02), settlement rail (USDC on Base only), per-answer billing even on empty results, pre-payment input validation, data freshness (up to 60 s old), upstream source (api.weather.gov), and an explicit non-affiliation/life-safety disclaimer. Annotations only cover read-only/idempotent safety, so this is genuinely additive.

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 price and the 'never executes' constraint, which is right. But it is one dense run-on with repeated facts ('USDC on Base only' appears twice) and a heavy parenthetical clause, so signal is interleaved with restatement.

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 carries the return contract and does so: enumerated alert fields, freshness window, empty-result billing, and safety disclaimers. What it omits is the actual quote payload shape (e.g., whether a 402 challenge or address is returned), which an agent calling a payment-quote tool might want.

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?

Zero-parameter schema means baseline is 4, and the description usefully explains the request shape the price covers: one point (?lat=38.9&lon=-77) or one state (?area=CA), with example values and the mutual exclusivity of the two modes. The mismatch that these inputs live outside the input schema slightly muddies it.

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?

The description opens with a specific verb+resource: it returns payment terms for a named endpoint, and explicitly scopes itself ('never runs the check or pays'). That cleanly separates it from the check/execution siblings, though it never names a specific sibling quote tool it pairs with.

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?

It states the operative rule clearly: pay the 402 over HTTP with x402 v2, and this tool only quotes. The cost model ('charged per answer, including when no alerts are active; bad input is refused before payment, not charged') tells the agent when a call is wasteful. It stops short of naming an alternative tool or an explicit 'do not use this if...' branch.

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