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

Annotations supply only destructiveHint=true, so the description adds real value: it discloses that the call 'may send invites to participants' (an external side effect not covered by annotations), notes calendar_id is sent as a query param, and documents the v3 endpoint. It still doesn't explain auth requirements or reversibility of a destructive-flagged create.

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?

Three tight sentences with the core action front-loaded and no filler. The endpoint URL is somewhat technical overhead but does orient the agent, so it is not wasted.

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 eight-parameter mutation with no output schema, the description covers the required calendar_id and the invite side effect but says nothing about the return value, error behavior, or permission/auth needs. Adequate but with clear gaps for a destructive-flagged create tool.

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 schema already documents all eight parameters including their types and the calendar_id query-param placement. The description's only repeated note about calendar_id being a query param adds nothing beyond the schema, so the baseline 3 applies.

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 names a specific verb and resource ('Creates a calendar event'), and the create action is easily distinguished from read/query siblings like nylas_get_event and nylas_list_events. It stops short of explicitly contrasting with the closest sibling (nylas_create_draft) or scoping the creation target.

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?

There is no explicit when-to-use guidance, no prerequisites, and no named alternatives. The description states mechanics but leaves the agent to infer that this tool is for new events versus retrieving or updating existing ones.

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