Create an event

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

The description adds critical behavioral context beyond the annotations: the AMBIGUOUS_ACCOUNT failure mode when `account` is omitted, and the instruction not to guess. Annotations correctly declare a non-destructive, non-idempotent write operation, and the description does not contradict them. However, it omits other useful behaviors — e.g., the default 'none' for send_updates (though that is in the schema) and whether the event is immediately visible or requires confirmation.

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 waste. The main action is front-loaded, and the failure-mode guidance is directly attached to the condition that triggers it. Every part of the description 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 a 13-parameter creation tool with 85% schema coverage and no output schema, the description covers the most agent-critical behavioral nuance: account ambiguity failure. It doesn't mention the return value (event ID) or default notification behavior, but those are largely covered by the schema. The description is complete enough for an agent to call correctly and handle the main error case.

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 85%, so the schema already documents most parameters (account, send_updates, timezone, recurrence, etc.). The description reinforces the account parameter's fallback behavior but doesn't add syntax or format details for other parameters beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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 opens with a specific verb+resource ('Create an event') and adds a scope qualifier ('on one account') that distinguishes it from sibling tools like update_event, move_event, or propose_schedule. An agent can tell this is for direct event creation without opening the schema.

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 clearly states the when-not condition — if `account` is omitted and multiple accounts are eligible, it fails with AMBIGUOUS_ACCOUNT and the agent should ask the user rather than guess. It does not explicitly name alternative tools (e.g., update_event, propose_schedule), but the guidance on account selection is clear and actionable.

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