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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, lowering the burden. The description adds value by explaining the tool's non-mutating actions (parse, describe, compute) and specifying the 5-field constraint. No contradictions with annotations exist.

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 only two sentences and is entirely front-loaded with the core actions. It includes a relevant example without any redundant words or filler, making every sentence earn its place.

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 rich input schema, annotations, and the presence of an output schema, the description is complete. It covers the input format, the computation behavior, and an example, leaving no significant gaps for an agent to understand and invoke the tool 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 schema covers all three parameters with detailed descriptions (100% coverage), so the baseline is 3. The description's example adds a concrete illustration but does not provide additional semantic depth beyond what the schema already states for fromIso and nextCount.

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 function with specific verbs: 'Parse a 5-field cron expression, describe it in plain English, and compute the next N fire times.' It precisely identifies the resource (cron expression) and the actions (parse, describe, compute), making it distinct from sibling tools like calculators and converters.

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 gives clear context by specifying the exact input format and an example: "Input the standard 'minute hour day-of-month month day-of-week' form (e.g. '0 9 * * 1-5' for weekdays at 9am)." It does not explicitly mention when not to use the tool or name alternatives, but no close siblings exist, so the guidance is sufficient.

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