When a cron expression fires

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it specifies the output includes local time, weekday, and UTC, and that runs in DST gaps or repeats are flagged. This helps the agent understand edge-case handling without contradicting the 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 two sentences with no redundant phrasing. It front-loads the core purpose (next runs), then adds essential details (time zone, output format, DST handling). Every sentence earns its place, and the structure is efficient.

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?

The tool has an output schema (not shown) and annotations covering safety and idempotency, so the description does not need to enumerate return fields. It provides key contextual details: time zone default, output formatting, and DST edge cases. It does not mention error conditions or the default count, but count is already in the schema. Overall, it is complete enough for an agent to invoke 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?

The input schema describes three of five parameters (from, count, dialect), leaving timezone and expression without descriptions (60% coverage). The description clarifies the timezone parameter by stating the default is UTC and explains 'from' as 'after a given moment or now'. It does not add details for count or dialect, but the schema already covers those. The description partially compensates for the coverage gap, so it meets the baseline of 3.

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 the verb 'list' (implied by 'The next runs of a cron expression') and the resource (cron expression), with details about time zone, output format (local time, weekday, UTC), and the starting point (after a given moment or now). It distinguishes this from siblings (convert_cron, explain_cron) by focusing on computing future executions rather than conversion or explanation.

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 when to use this tool (when you need the next execution times of a cron expression), but it does not explicitly contrast it with sibling tools or state when not to use it. There is no mention of alternatives or conditions that would route an agent to convert_cron or explain_cron. The guidance is implicit rather than explicit.

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