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

Annotations declare destructiveHint=true, idempotentHint=true and openWorldHint=true; the description adds real context by explaining timezone-based display and the availability-verification caveat. It never addresses the most consequential annotation signal, however: why adding an option is flagged destructive (e.g. whether existing proposed options are replaced or overwritten), nor how idempotency is achieved via requestId.

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 compact sentences with the core operation stated first and the constraints folded in afterwards; very little waste. The timezone sentence is slightly cryptic (which entity's timezone?) but it 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 seven-parameter, non-read-only, destructive-flagged mutation with no output schema, the description leaves major gaps: parameter meanings, the destructive side effects, and what the tool returns (a created option, an id, an error on conflict). It covers timezone and availability caution but not enough for confident invocation.

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 0%, so the description must explain all seven parameters, yet it only touches start/end formatting (which the schema's date-time format and regex already enforce). eventId, participantId, requestId, agent and label are entirely unexplained, leaving the agent to guess that requestId is an idempotency key and label is the option's display text.

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 and object ("Add a date option with ISO 8601 start and end"), which tells an agent this mutates an event's date options rather than voting or removing them. It is close to sibling-distinguishing (remove_date, vote), but never names the alternatives, so it stops short of a 5.

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?

"Check accessible calendars and propose suitable options autonomously" gives behavioral direction, and "do not claim unverified availability as certain" sets a confidence rule. However, there is no statement of when to call this versus vote, set_availability, or remove_date, and no preconditions such as required permissions or that the event must exist.

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