update-calendar-event

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

Annotations already establish this is a non-read, non-idempotent operation, and the description adds valuable behavior beyond that: partial-field update semantics, attendee notification side effects, and the confirm=true safety gate. No contradiction with annotations (readOnlyHint=false aligns with 'WRITE operation'). It stops short of covering failure behavior for nonexistent eventIds, but the added context is substantial.

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 tight sentences with zero filler. The core purpose is front-loaded, the patch semantics and notification side effect fit naturally in the first sentence, and the WRITE/confirm gate is a crisp standalone second sentence. Every clause earns its place.

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 an 11-parameter mutation tool, the description covers purpose, scoping semantics, side effects, and the confirmation gate, and the schema fully documents parameters. It does not explicitly state behavior for invalid eventIds or error responses, and it leaves sibling differentiation implicit, but nothing an agent needs to invoke the tool correctly 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 baseline is 3. The description reinforces the confirm=true requirement already documented in the schema and adds the mental model that omitted fields are left unchanged. It does not add meaning beyond that, but none is needed given the schema's thorough per-parameter documentation.

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 a specific verb (UPDATE) with a specific resource (existing calendar event), and the parenthetical clarifies partial-update semantics. This clearly differentiates it from sibling tools like create-calendar-event, get-calendar-event, and respond-to-calendar-event without needing to read their schemas.

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 word 'existing' plus the WRITE designation imply when to use it versus read or create tools, and 'only the provided fields change' clarifies patch-style usage. However, there is no explicit when-not guidance or naming of alternatives (e.g., 'to create a new event use create-calendar-event'), leaving the routing decision to inference.

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