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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive write. The description usefully adds that events attach to the variant and that start/end are optional (scheduled or left as ideas), which is real behavioral context. It does not cover permissions, duplicate-handling, or what the call returns.

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 with zero filler, front-loaded with the core action and immediately followed by the scoping constraint. Every clause carries information an agent needs.

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?

For a write tool with full annotation coverage, a complete input schema, and no output schema, the description is largely sufficient. The remaining minor gap is that it never clarifies the created-event return or duplicate behavior, but nothing critical for correct invocation is missing.

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%, so the schema fully documents the three parameters including the nested data object. The description's mention of optional start/end scheduling loosely maps to the start/end fields but adds no syntax or format detail beyond the schema, so baseline 3 applies.

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?

Clear specific verb+resource ('Add ... a museum, concert, restaurant, tour or activity') that concretely defines what an event is. It also distinguishes itself from add_destination by stating events belong to the variant rather than a single destination, though it does not explicitly separate itself from update_event or toggle_event.

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?

Usage context is implied ('Add something to do during the trip') and the variant-vs-destination routing hint helps. However, there is no explicit when-to-use vs when-not guidance relative to siblings like update_event, toggle_event, or add_destination.

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