calendar.events.add

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

Annotations are absent, so the description carries the full disclosure burden. It opens with 'SIDE-EFFECTFUL', warns 'NOT idempotent — calling this twice creates two events', explains why naive timestamps are rejected, and states the return value. This makes the side-effect and idempotency profile transparent before invocation.

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?

Four dense sentences lead with the most decision-relevant fact (side-effectful/non-idempotent), then move to preconditions, return value, and recommended follow-up. Every sentence earns its place with no filler or repetition.

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?

The tool is moderately complex (8 params, no annotations, no output schema), yet the description covers side effects, idempotency, timestamp constraints, return shape, and the recommended next step. There is little an agent needs to safely invoke it correctly; only explicit error behavior for nonexistent entities is absent, which is minor.

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?

The input schema already documents all 8 parameters, so the baseline is 3. The description adds value by explaining rejection semantics for naive starts_at/ends_at timestamps and clarifying the 'one-off' nature of the window. It doesn't add much for entity, notes, source, or original_timezone, but the schema already covers those.

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 ('Add') and resource ('one-off time window'/'event') with concrete examples such as downtime, maintenance, and shift. It clearly differentiates from sibling event tools (update/delete/list/conflicts) by framing the action as creating a new event, and it highlights non-idempotence as a distinguishing trait.

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?

It states the context for use: adding one-off time windows to an entity, and it explicitly directs the agent to follow up with calendar.events.conflicts for overlap checks. It also establishes a hard precondition (ISO 8601 with explicit timezone) that an agent must verify before calling. It does not explicitly mention alternatives like events.update for modifications, but the sibling separation is otherwise clear.

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