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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior. The description adds meaningful context beyond that: the valid pos range, a per-call price of $0.001 USDC via x402 on Solana, and an equivalent HTTPS endpoint. It does not describe the exact return shape, but it does disclose the payment and access model that an agent must know before calling.

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 compact and mostly front-loaded: definition, clarifying examples, range, then price and endpoint. The examples are useful rather than redundant, and the pricing/endpoint details are operationally relevant, though the opening phrase is slightly cryptic before the examples clarify it.

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 one-parameter computational tool with no output schema, the definition, examples, range, and payment/endpoint details provide enough context to call it correctly. The main remaining gap is that the exact return structure is only implied by the examples rather than stated explicitly.

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 does this well by defining pos as a place counted from 1 on the left, giving concrete examples, and stating the valid range 1 to 999999999999, which matches the schema bounds.

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 states a specific concept: given a position pos, it reports where that position sits inside its containing integer, with examples mapping place 10 to position 1 of 10 and place 12 to position 1 of 11. It is clear enough to distinguish from generic digit tools, though it never explicitly names the Champernowne constant or directly contrasts with champernowne_digit and related siblings.

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 explains what the tool computes but gives no explicit guidance on when to use it rather than champernowne_digit, champernowne_owner, champernowne_start, or champernowne_len. Usage is only inferable from the definition and examples.

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