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

The annotations already declare that this is read-only, idempotent, open-world, and non-destructive. The description adds useful behavioral context beyond the annotations: pricing at $0.001 USDC per successful x402 call on Solana and an equivalent HTTPS endpoint, though it does not discuss rate limits or response format.

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 definition is front-loaded with the core computation, then gives examples, bounds, pricing, and endpoint details. It is appropriately sized overall, though four worked examples are slightly more than strictly necessary.

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?

For a simple one-parameter mathematical tool, the description covers the computation, input range, examples, and payment model. Since there is no output schema, it could more explicitly state that the return value is an integer digit count, but the first sentence strongly implies it.

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 description coverage is 0%, so the description must carry parameter meaning; it defines m as the upper bound in 'from 1 through m,' states the valid range 1 to 999999999999, and gives concrete examples for m=9, 10, 13, and 100. It mostly restates the schema's min/max but compensates adequately for the missing parameter description.

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 precisely states what is computed: the number of digits used to write integers from 1 through m, reinforced by worked examples. It is clear but does not explicitly distinguish this from sibling Champernowne tools such as champernowne_digit, champernowne_owner, champernowne_place, or champernowne_start.

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 gives examples, a valid range for m, price, and an HTTPS endpoint, but no explicit when-to-use guidance or comparison to alternative tools. An agent must infer that this tool is specifically for the digit-count computation rather than other Champernowne-related operations.

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