Cron Next Runs

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

Although annotations already declare readOnlyHint and idempotentHint, the description adds valuable behavioral detail: the Vixie day-of-month/day-of-week OR rule and explicit rejection of non-standard syntax like L, W, and #. This goes well beyond the structured annotations and helps an agent predict edge-case behavior.

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: purpose first, then the key edge-case rule, then the syntax rejection policy. The trailing web link is not necessary for tool invocation, so it slightly dilutes conciseness, but overall the text is efficient and well organized.

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 description covers the input format, timezone handling, the most important cron parsing subtlety, and error behavior for unsupported syntax. It does not explicitly describe the return shape, but no output schema exists and 'list its next run times' is reasonably clear. There is a minor internal inconsistency: it says 'standard 5-field cron expression' yet the schema example includes '@daily', which is not a 5-field expression.

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 only 33%, so the description must compensate. It explains the expression and timezone semantics, but it does not mention the count parameter at all. Count is partially inferable from the schema's default and bounds, but the description adds nothing about how many runs will be returned.

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 uses a specific verb and resource: 'Parse a standard 5-field cron expression and list its next run times in a timezone.' This clearly distinguishes the tool from all sibling utilities, which are unrelated generation, encoding, hashing, and formatting tools.

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 the tool: whenever an agent needs to compute upcoming cron schedules. It does not explicitly state when not to use it or name alternatives, but no sibling tool serves a similar purpose. The rejection of non-standard syntax provides some usage boundary.

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