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

Adds a behavioral guarantee ('preserve timezone and all-day semantics instead of guessing them'), which is useful. Annotations already cover mutability and non-idempotency, so the description adds a bit of extra context but not extensive behavior like side effects or response details.

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, front-loaded with the main purpose, and no wasted words. The required fields and behavioral note are efficiently stated.

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 complex tool with 16 parameters and nested objects, the description is sparse. It does not cover optional parameters or return expectations, though the schema has some descriptions and the behavioral note about timezone/all-day helps. Still, an agent may lack guidance on many optional fields.

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?

Description mentions only required parameters (title, attendees, start, end) and a timezone note, but does not explain the many optional parameters (location, conference, recurrence, visibility, etc.). With schema coverage at 31%, it fails to compensate for the gaps, adding minimal value beyond the schema's own descriptions.

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 (Create), resource (event), and scope (one resolved calendar), clearly distinguishing from calendar_create_calendar and calendar_update_event. It also mentions required fields and a behavioral nuance, making the purpose unmistakable.

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?

Implies usage for creating events; does not explicitly compare with siblings like calendar_update_event or calendar_cancel_event, but the purpose is clear and no exclusions are needed. The 'one resolved calendar' hint suggests it is not for multi-calendar operations.

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