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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), so the bar is lower, and the description adds real behavioral context: timezone is stored as-is and not replaced by the user timezone, and waitSync=true blocks until the external calendar syncs so the response can carry links while false returns immediately with links possibly absent. It omits auth requirements, external-calendar side effects, and rate limits, so not a 5.

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?

Front-loaded with the required field and format rules, and roughly 110 words for a 12-parameter tool is proportionate. It is dense but each clause maps to a parameter concern; the parameter list reads as one long run-on rather than scannable structure, keeping it out of 5 territory.

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?

An output schema exists, so return values need not be explained, and annotations cover safety. The description supplies the format/default/sync semantics an agent needs to call it correctly, but it never mentions calendarId or allDay despite them being caller-relevant inputs, leaving a small completeness gap.

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 12 parameters with formats, enums, and defaults. The description largely restates the schema (ISO 8601 formats, title 1–200 chars, status/type values) and adds only marginal nuance, so the baseline 3 is correct.

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?

Opens with a specific verb and resource: "Create an event or task for the authenticated user." Combined with sibling tool names (update_event, set_event_status, delete_event, save_note/save_flow), an agent can immediately tell this is the creation path for calendar items as opposed to mutation or deletion.

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?

Usage is only implied. The description never states when to pick this tool over save_flow, save_note, or update_event, and it does not explain the event-vs-task choice beyond naming the two enum values. The one genuine decision aid is the waitSync trade-off ("true waits for the external calendar... false responds immediately and links may be absent"), which tells the agent when to trade latency for links.

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