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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true and idempotentHint=false, and the description is consistent with all of them ('Reads or computes only and changes nothing'). It adds information annotations cannot carry: per-call pricing via x402 USDC or card key, 25 free calls, failed calls free, and that repeated calls incur cost again — genuinely useful before an agent loops on it.

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?

Front-loaded with the purpose, then syntax support, use case, example, then cost. Dense but nearly every clause carries information; the pricing sentence is longish yet relevant to call decisions.

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?

No output schema exists, and the description does state the return is next run times in UTC, plus the syntax accepted for the required parameter and the cost model. Count/from behavior is left to the schema, which adequately documents it, so an agent has enough to call correctly.

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 coverage is 100%, so baseline is 3; the description earns an extra point by spelling out the 5-field cron grammar (minute hour day month weekday) and that ranges, lists, steps and names like MON/JAN are accepted, which is semantics the schema's bare 'The cron expression' does not provide. It says nothing about 'from' or 'count', but those schema descriptions are adequate.

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?

States a specific verb and resource ('next run times of a standard 5-field cron expression') and immediately scopes it with the supported syntax and UTC output. No sibling tool covers cron, and the definition makes the scope unmistakable anyway.

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?

Gives a concrete use case ('check a schedule before deploying it') and a worked example expression. There are no competing cron siblings to route away from, so the absence of explicit exclusions costs little.

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