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

Beyond the readOnlyHint annotation, the description discloses important behavioral details: standard timezone abbreviations are required, partial names like 'Pacific' will not parse, and the returned time/time_12h fields are local while utc_iso is needed for triggers. This gives the agent essential execution context that annotations alone do not provide.

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 well structured with a front-loaded summary, concrete use cases, an important warning, and a returns section. Every part adds necessary information, and the critical trigger-time warning is clearly marked as IMPORTANT.

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 low complexity, single parameter, and readOnly annotation, the description fully covers what an agent needs: usage context, parsing constraints, output field meanings, and the UTC danger case. The returns block compensates for the absence of an output schema.

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 already documents the single expression parameter with examples at 100% coverage. The description adds further value by supplying additional relative-expression examples, clarifying timezone abbreviation requirements, and explaining how the expression maps to different output fields, especially utc_iso for triggers.

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 and resource: resolving a natural language or relative date/time expression into an actual date and optionally time. It clearly distinguishes its role from sibling tools by noting it should be used before searches, calendar events, or any operation needing a concrete date. The timezone conversion purpose is also explicit.

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 explicit when-to-use guidance for relative expressions, timezone conversions, and date-requiring operations like create_calendar_event. It does not provide when-not-to-use guidance or name a directly competing alternative, so it falls just short of a 5.

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