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

Annotations already declare readOnlyHint=true associative, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds valuable context: it discloses that a missing id and an id owned by someone else both return not found, preventing the agent from expecting an error or different behavior for 'not found' cases. It also notes that dates use the user timezone, which is useful but not critical.

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 sentences, each with a clear purpose: identifies the action and ownership, clarifies error behavior, and notes date handling. No wasted words; the key constraint (ownership) is front-loaded.

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 simple single-parameter read tool with a full output schema and safety annotations, the description is largely sufficient. It does not explain the return format, but the output schema exists, so that is covered. It also does not describe pagination or errors in detail, but for a single-event fetch that is not necessary. The ownership scoping is well-covered.

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 100%: the schema already describes the id parameter and its semantics (owned by the user, any other id returns not found). The description adds no additional parameter-level detail beyond what the schema provides, so a baseline of 3 is appropriate.

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 ('Get') and resource ('one event owned by the authenticated user by id'), immediately distinguishing it from siblings like 'search_events' or 'list_calendars' by emphasizing ownership and single-id lookup. It also clarifies the core scope: only events owned by the user are accessible.

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?

It provides clear context: this tool fetches exactly one event by id, and implies it is not for listing or searching (which have dedicated siblings). However, it does not explicitly say when NOT to use it (e.g., for lists or searches) or mention alternatives, though the sibling list and tool naming make the distinction obvious.

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