calendar_events_add

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

With no annotations, the description carries the full load and does so well: it flags the write as side-effectful, warns it is NOT idempotent (duplicate calls create duplicate events), and explains that naive timestamps are rejected and why. It omits permission/auth requirements and whether the target entity must already exist.

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 tight sentences, each carrying distinct information; the side-effect and non-idempotency warnings are front-loaded before the parameter constraints and the follow-up pointer. No filler.

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 5-required-parameter mutation tool with no annotations and no output schema, it covers the critical risks (duplication, timezone format, return field) and names the natural next call. It could still say more about failure modes, entity resolution, or permissions.

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 coverage is already 100%, so the baseline is 3, but the description adds real meaning: the timezone requirement is stated as a hard rejection rule with rationale (ambiguity once stored as UTC), and it documents the returns shape. It adds no clarification for entity, type, notes, source, or original_timezone beyond the schema.

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 and resource ('Add a one-off time window ... to an entity') and enumerates concrete examples (downtime, maintenance, delivery, shift). An agent can distinguish it from calendar_events_update/delete/list and from calendar_entities_* without opening any 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?

Explicitly routes the agent to the sibling calendar_events_conflicts for overlap checking, and the 'one-off' qualifier implies when this tool is appropriate. It stops short of stating exclusions, e.g. that recurring schedules should not go through this tool.

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