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

No annotations are provided, and the description discloses no behavioral detail such as input handling, edge cases, or return semantics. The phrase 'Length of hailstone' is too terse to tell the agent what the tool actually computes or how it behaves at boundaries.

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?

The description is very short and wastes little text, but it is also under-specified: 'Length of hailstone' is not a complete operational statement. It is concise in length but not in informational density.

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?

Given the tool's simple schema and absent annotations, the description should at least clarify what input the tool acts on and what the length represents. The current description leaves too much unspecified for an agent to invoke it confidently, especially alongside many number-theory siblings.

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?

The input schema has zero parameters, so there are no parameter semantics to document. With zero params, the baseline is 4, and the description does not introduce any parameter confusion.

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 'Length of hailstone' names a specific resource (hailstone) but is circularly tied to the tool name, which already says hailstone-length. It is plausible as a math operation, but it does not use a distinct verb or explain what 'length' means in this context, so a 3 is fair.

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 guidance is given on when to use this tool versus sibling alternatives. The description does not differentiate it from similar math/number tools such as x402-hailstone-max or x402-collatz, leaving the agent to guess the intended use case.

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