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

Annotations declare readOnlyHint=true and idempotentHint=true, so the description need not repeat safety. It adds context about searching from a starting date but lacks details on behavior when an event has already occurred on the start date (e.g., does it skip to next day?). No contradiction 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, zero wasted words. The first sentence captures the core functionality, the second provides practical use cases. Front-loaded and efficient.

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 no output schema, the description could mention return format or timezone handling, but the schema covers response_format and timezone. Mostly complete for a read-only lookup tool with rich annotations.

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 description coverage is 100% with all parameters well-documented. The description adds little beyond listing event types and implying date/count usage, so baseline 3 is appropriate.

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 uses specific verbs ('Find the next occurrence(s) of a sun event') and explicitly lists all event types. It clearly distinguishes from siblings by focusing on 'next occurrence' of a single event, unlike astro_get_sun_times which returns all events for a day.

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 concrete use cases ('when is sunset today?', 'planning golden-hour photography'), but does not explicitly mention when not to use it or suggest alternatives like astro_get_sun_times for multiple events.

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