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

The annotations already cover safety and idempotency, while the description adds important behavior: payment of $0.001 USDC per successful call, Solana x402, and the equivalent HTTPS endpoint. It also documents the short-form convention for trailing 1s, which affects what result is returned.

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 front-loaded: definition, examples, output convention, pricing, and alternate endpoint. Every sentence adds useful information and there is no 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?

For a simple one-parameter mathematical tool with annotations, the description covers purpose, examples, output notation, pricing, and access method. It is slightly incomplete about the exact input string format and the serialized return representation, which matters because no output schema is present.

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?

With only one parameter and 0% schema description coverage, the description partially compensates by saying it accepts a non-negative rational and showing examples like 13/8 and 355/113. However, it never explicitly maps that to the `value` parameter or specifies the exact string syntax and maxLength constraint.

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 clearly states that this computes the continued fraction expansion of a non-negative rational using the Euclidean algorithm. It gives concrete examples, but it does not explicitly distinguish the tool from close siblings such as cf_value, cf_convergent, or cf_sqrt.

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?

There is no explicit guidance about when to use cf_expand instead of related continued-fraction tools, nor are there stated prerequisites or exclusions. The examples show what it does, but not when an agent should choose it.

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