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

With no annotations provided, the description should disclose side effects, read-only nature, or constraints. It only says 'preview,' implying no modification, but does not explicitly state that the tool is safe and non-destructive. It also fails to mention timezone handling, error cases, or the 5-field constraint.

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 a single sentence with no waste, making it easy to parse. However, it is perhaps too concise; it could include a brief note about the count default or timezone behavior without sacrificing clarity. It front-loads the core action but misses ancillary details.

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?

Given the tool has 4 parameters, no output schema, and many sibling cron tools, the description is incomplete. It does not explain the return format (timestamps?), error handling for invalid expressions, or behavior when from_time is provided. Users would need to infer or test these aspects.

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 25% (only from_time has a description). The tool description hints at 'N' (matching count) and '5-field cron expression' (matching expr), but does not detail defaults or constraints for count and timezone. It adds modest value by emphasizing the 5-field limitation, but overall does not compensate for the low schema coverage.

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 tool's purpose: 'Preview next N execution times for a 5-field cron expression.' It specifies a specific verb (preview) and resource (execution times), and the 'N' parameter implies configurability. This distinguishes it from sibling tools like cron_describe (which describes format) and cron_parse (which parses components).

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 provides no guidance on when to use this tool versus alternatives like cron_describe or cron_matches. It does not mention prerequisites, typical use cases, or that it is intended for checking future runs rather than describing syntax or checking matches.

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