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

With no annotations, the description carries the full behavioral burden and does disclose two useful traits: the endpoint is public/no-auth, and it is not the payment path (mutations live at POST /v1/topup). It stops short of stating plainly that the operation is a side-effect-free read, but the content makes that evident.

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?

Two dense sentences, front-loaded with the free-tier and rate information an agent is most likely to need, ending with the routing caveat. The parenthetical rate list is information-dense but relevant rather than 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, no parameters, no annotations, so the description has to carry the payload meaning — and it does convey the actual pricing facts (5 free watches at >=300s, per-day rates, prepaid balance via x402/USDC on Base). An agent has enough to answer pricing questions and to redirect payment attempts.

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 parameters, so the baseline of 4 applies. Nothing in the schema needs elaboration and the description correctly does not invent parameter details.

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 makes clear this tool surfaces Ned Watch's pricing schedule (free tier, per-day rates) and is distinguishable from siblings like balance and watch_register. The verb is implicit (it never literally says 'returns the pricing schedule'), but the resource and scope are unambiguous.

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 'Public, no key needed' and explicitly routes payment actions elsewhere: 'Paying is done against POST /v1/topup/{5,20,50}, not here.' That is a genuine when-not-to-use-this signal tied to an alternative. It does not, however, describe when an agent should prefer this over the sibling 'balance' tool.

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