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

Annotations already establish readOnly, openWorld, idempotent, and non-destructive behavior, so the description need not repeat those. It adds meaningful behavior: output includes a plain-English explanation plus next run times, with time-zone handling and supported syntax features. Edge-case behavior is not mentioned, but that is minor for a read-only utility.

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 front-loaded: purpose, use case, then supported features. The 'Price: free' sentence adds little, but the rest is tight and scannable without unnecessary elaboration.

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?

For a simple read-only tool with three parameters and no output schema, this description supplies the purpose, output shape, supported syntax, and time-zone behavior. An agent has enough information to select and invoke cron_explain 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?

With 0% schema description coverage, the description carries the parameter burden. It communicates that expression is a cron string, tz is 'any time zone', and count controls 'next N run times'. It does not document defaults, constraints, or IANA time-zone format, but the core parameter meanings are clear.

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 opens with a concrete verb-object pair: 'Explain a cron expression in plain English and list its next N run times.' It also specifies supported cron variants and extensions, making the tool unmistakable among siblings like tx_explain or time_convert.

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?

It gives a clear practical context—'catch a schedule mistake before it fires at 3 am'—and states the core use case of validating and understanding cron schedules. It does not explicitly name alternatives or exclusions, but no sibling covers cron semantics, so the implied guidance is sufficient.

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