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

Annotations already declare read-only, idempotent, non-destructive, and open-world behavior. The description adds meaningful behavioral context beyond that: pricing ('$0.001 USDC per successful call'), payment protocol (x402 on Solana), and an equivalent HTTPS endpoint. It does not contradict annotations.

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 front-loaded with the core definition and examples, followed by practical invocation details such as range, price, and endpoint. It is somewhat dense but every sentence contributes useful context; no major redundancy or wasted preamble.

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 predicate with no output schema, the description supplies the definition, examples, domain, and cost/transport details. Completeness is slightly reduced by not explicitly stating the Boolean return behavior or distinguishing the sibling 'practical_count', but the core invocation needs are covered.

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 identifies n as the value being tested and restates the valid range 1 to 1000000000000, but that range is already encoded in the schema's minimum/maximum, and it does not add further format or semantic detail beyond the mathematical definition.

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 gives a specific predicate ('Whether n is practical') and defines the mathematical property with examples, so the agent can understand what is being tested. It does not explicitly differentiate the tool from the directly related sibling 'practical_count', which prevents a 5.

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 implies usage through the predicate definition and examples, and it states the valid input range. However, it does not say when to choose this tool over alternatives such as 'practical_count' or mention any exclusions, so guidance remains only implicit.

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