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

The description discloses important behavioral traits beyond annotations: it states that a missing id and an id owned by someone else both return not found, which clarifies error behavior. It also explains the effect of occurrenceDate on repeating tasksholistically. While annotations already declare idempotentHint and destructiveHint, the description adds valuable context about ownership and not-found semantics, enhancing the agent's understanding of side effects.

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?

The description is concise, at three sentences, with the most critical information (purpose and status values) front-loaded. It avoids repetition of schema details and includes only essential behavioral notes. Every sentence adds value, and the structure is clean and scannable.

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?

The description is complete for its complexity: it explains the purpose, the parameters' usage, and special behaviors (repeating events and not-found handling). The output schema exists, so return values are likely covered elsewhere, and the annotations provide safety hints. Nothing critical is missing for an agent to call this tool correctly.

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?

The input schema already describes all three parameters with 100% coverage, including the allowed enum values and the ISO 8601 format for occurrenceDate. The description adds meaning by explaining that 'status' maps to the enum and that occurrenceDate is specifically for repeating events to isolate a single day. This goes beyond the schema's basic descriptions, so it earns above the baseline of 3.

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 clearly states a specific verb and resource ('Set status of an event owned by the authenticated user'), which defines the tool's purpose well. It also distinguishes from sibling tools like update_event by focusing solely on status changes. The allowed statuses are enumerated, leaving no ambiguity about scope.

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 explicitly specifies when to use this tool (to change status) and provides a key conditional: 'For a repeating task pass occurrenceDate... so only that day changes.' It also implies when not to use it by focusing on status only, differentiating it from update_event for other fields. This is direct guidance that aids selection without needing to inspect siblings.

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