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

No annotations are supplied, so the description carries the disclosure burden. It adds genuinely useful behavior beyond a bare name: the default period of 14 and the pricing gate ('5 free trial calls per signed wallet'). It does not say what the result contains, whether errors occur on mismatched array lengths, or what units the output uses.

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 compact sentences put the definition and required inputs first, followed by the default value, then the trial-call note. No filler, though the emoji-bearing promo line is peripheral to invocation correctness.

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?

Weak due to the undocumented 'values' parameter and unclear array string format against 5 parameters at 0% schema coverage.

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, and it does explain high/low/close arrays and the optional period default. However, the fifth parameter 'values' is never mentioned, leaving unclear whether it is an alternative combined input or something else, and the comma-separated string format the schema implies is not clarified.

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 (Calculate) and resource (Average True Range), and expands the acronym plus labels it a volatility indicator, so the agent knows what it produces. It does not distinguish itself from volatility-adjacent siblings like x402-bollinger-bands or x402-standard-error, but the purpose itself is 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?

The description tells the agent what inputs to supply ('Provide high/low/close price arrays and an optional period (default 14)'), which implicitly describes how to invoke it. There is no guidance on when to pick ATR over sibling indicators such as x402-sma or x402-bollinger-bands, and no preconditions or exclusions.

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