Get a calendar

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

Annotations already establish that the operation is read-only and idempotent. The description adds useful behavioral context beyond those hints, particularly the constraint that it only works for calendars already on the user's list and the guidance to interpret event times using the returned timeZone. No contradictions with annotations.

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 compact: one sentence enumerates the returned fields and one sentence covers the limitation and fallback. Every clause earns its place, and important constraints are 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 read-only tool with one required parameter, the description covers the return fields, the key caveat about calendar-list membership, and the recommended alternative for out-of-scope calendars. There is no output schema, so enumerating fields is valuable and sufficient.

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 single parameter calendar_id is already fully documented in the schema (100% coverage), including the 'primary' special value. The description reinforces the 'user's list' context but does not add substantial parameter-level meaning beyond the schema.

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 uses a specific verb ('Fetches') and identifies the resource as 'one calendar-list entry', followed by an explicit list of returned fields (summary, description, timeZone, accessRole, defaultReminders, primary). This clearly distinguishes it from list_calendars and other siblings.

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 explicitly states the tool's scope ('Works only for calendars on the user's list') and provides a precise alternative for a known edge case: use raw_request with path calendar/v3/calendars/<id> for a shared calendar never added to the list. This tells the agent exactly when to choose this tool versus another.

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