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

With no annotations, the description carries the full burden. It does disclose a real behavioral trait not available elsewhere: a pricing/auth model ('5 free trial calls per signed wallet'), which tells the agent a signed wallet is needed. However, it says nothing about output format, unit handling, or the decay formula/model used, leaving significant behavioral gaps for a zero-annotation tool.

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?

One dense front-loaded sentence delivers purpose plus parameters, followed by a short payment note. It is well sized for a simple calculator, with the minor promo tail being the only 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 and no annotations mean the description should say more about what comes back. It implies a single remaining-quantity value, but omits the formula applied and the units of the result, leaving an agent to guess how to interpret the response even though the input meanings are covered.

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 0%, so the description must compensate. It does map all three parameters to meanings (initial amount, elapsed time, half-life), which is genuinely useful given the bare string-typed schema. But it gives no units, expected string format, or sign/precision conventions, so an agent still can't be sure whether 'time' is in the same units as 'halfLife'.

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 (computes) and a specific output (remaining quantity after decay) plus the three inputs that produce it. This clearly differentiates it from siblings like x402-decay-constant, x402-half-life, and x402-doubling-time, though it never explicitly names an alternative.

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?

No when-to-use or when-not-to-use guidance is given. An agent must infer that this is a physics half-life decay calculation and decide on its own when it beats x402-decay-constant or x402-half-life.

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