Explain a cron expression

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

Annotations already mark the tool as read-only (readOnlyHint=true). The description adds value by disclosing that the output includes both a plain English translation and a list of upcoming runs, and that the interval is explicitly reported to highlight potentially problematic schedules. No contradictions with annotations.

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?

Two sentences, each serving a distinct purpose: first sentence states the core function, second sentence adds technical scope and a practical benefit. No redundant or filler content.

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 tool's purpose, parameters, and output features (plain English, next runs, interval). Given the absence of an output schema, it adequately communicates what the user will receive. A minor gap is the lack of error handling information (e.g., invalid expression), but for a tool of this simplicity, the description is largely complete.

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 descriptions (100% coverage). The description adds context beyond the schema by explaining that the expression can be 5 or 6 fields, and that the timezone uses IANA names. It also adds the output feature of reporting the interval, which is not in the schema.

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 that the tool translates a cron expression into plain English and lists next scheduled runs, specifying it handles both 5-field and 6-field syntax. This specific verb+resource description distinguishes it from all sibling tools, which cover different domains like HTTP requests, JWT decoding, hashing, etc.

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 usage when a cron expression needs interpretation, and notes an additional use case: reporting the interval to catch accidentally too-frequent schedules. While no explicit when-not-to-use or alternatives are provided, the sibling tools are sufficiently distinct that no further guidance is needed.

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