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

The description states 'Computed in the Worker; no network call,' which directly contradicts the annotation 'openWorldHint: true' (indicating external open-world interaction). This is a significant inconsistency.

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 with the core purpose, followed by necessary details (field count, supported features, computation context, pricing). Every sentence contributes without redundancy.

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 tool's complexity, the annotations, and the presence of an output schema, the description is complete enough for an agent to call it correctly. It covers input format, output content (plain English explanation and next runs), computation context, and pricing model, leaving no critical gaps.

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 100% schema description coverage, the baseline is 3. The description adds meaningful detail about the 'expression' parameter (five or six fields, seconds first, names like MON/JAN, and steps), which goes beyond the schema's generic 'Cron expression, 5 or 6 fields'. It does not add much for 'tz' or 'count', but the added value for the main parameter justifies a 4.

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 states a specific verb ('Explains') and resource ('cron expression') and clarifies it lists next runs. It clearly distinguishes itself from sibling tools like timezone or date_calc by focusing on cron syntax parsing.

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 provides clear context about what the tool does (explains cron expressions, lists next runs) and mentions supported syntax (five/six fields, names, steps). However, it does not explicitly state when to use it versus alternatives or any exclusions, though the purpose is unambiguous.

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