Cron next runs

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: a 366-day lookahead ceiling, strict-after semantics, and which syntax is rejected (L, W, #, named months) — useful limits not present in the structured fields.

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?

Three dense sentences with no filler; the core action and its scope lead, supported features and rejections follow, and the negative boundary closes it out. Every clause carries an actionable constraint.

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?

With an output schema present, return values need no explanation, and the required-parameter contract plus input constraints are well covered. The only unaddressed area is failure behavior for invalid expressions or mismatched dialect syntax, which the agent must infer.

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 20%, so the description must carry the load, and it largely does: it maps count (1–10), after (UTC instant, strictly after), zone (IANA), and dialect (GitHub/Cloudflare/Quartz/AWS, matching the enum), and describes expression syntax and exclusions. It does not tie dialect-specific quirks to specific dialect values, leaving a small gap.

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 (Preview) plus resource (1–10 cron matches) and scopes it precisely: strictly after a UTC instant, within 366 days, in an IANA zone. The closing sentence 'does not install or run a schedule' explicitly separates it from the scheduling-oriented sibling recurring_schedule.

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?

Usage context is clear from the supported dialects and the stated boundary that it neither installs nor runs schedules, which is the key when-not condition against recurring_schedule. It stops short of an explicit 'use this tool when…' routing statement, so 4 rather than 5.

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