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

Annotations only declare readOnlyHint=true, and the description adds substantial context beyond that: the local-vs-UTC distinction between the time/time_12h and utc_iso fields, the critical warning to use utc_iso for trigger_at, and the parsing limitation that full names like 'Pacific' won't work. These are exactly the behavioral traits an agent needs to avoid silent errors.

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?

Front-loads the core purpose, then layers timezone conversion and the utc_iso warning in a logical order, with summary/returns tags aiding scanning. Slightly long, but nearly every sentence carries non-redundant operational value.

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?

Although no formal output schema exists, the description includes a returns section describing the dict fields (date, weekday, time, time_12h, utc_iso), so the agent knows what comes back and how to use it. Combined with usage and parsing caveats, the definition is complete for a 2-parameter read tool.

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?

Schema coverage is 100% so the baseline is 3, but the description adds meaning beyond the schema by constraining the expression format (standard timezone abbreviations required, examples given) and clarifying the timezone-conversion semantics. It does not elaborate on on_behalf_of, which the schema already documents, keeping it above baseline but not a full 5.

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?

States a specific verb (resolve) and resource (natural language date/time expression) with concrete examples, and explicitly distinguishes itself from siblings like create_calendar_event and add_trigger by describing itself as a prerequisite conversion step. An agent can identify its role without opening the schema.

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?

Explicitly states when to call it (before search queries, create_calendar_event, or any operation needing a concrete date) and adds a second distinct use case (timezone conversion). It even names the downstream consumer add_trigger and how to feed it, leaving nothing to inference.

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