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

Annotations declare readOnlyHint=true, so the safety profile is already known. The description adds useful behavioral context: it lists the specific fields returned, notes the optional account parameter behavior (omit to list all accounts), and discloses the reconnection failure mode. It doesn't describe pagination or rate limits, but for a simple read-only list tool, the added context is solid.

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 earning its place: what it returns, how to use it with a sibling, and what to do on failure. The most important information is front-loaded, and there is zero filler.

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 read-only list tool with one optional parameter and no output schema, the description is nearly complete. It covers the return fields, the usage flow, and the failure mode. The only minor gap is that it doesn't describe the exact output format or whether the response is grouped by account, but the description's explicit field list largely compensates for the missing output schema.

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% and the single optional parameter 'account' is already described in the schema. The description adds value by explaining the omission behavior ('Omit to list calendars for all connected accounts') and by tying the parameter to the real-world concept of a connected Google account. This goes beyond the schema's basic description.

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 the tool lists calendars in the user's connected Google account(s) and specifies the exact fields returned (name, id, primary status, access role). It also distinguishes itself from the sibling get_calendar_events by explicitly saying to use it before reading events.

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 tells the agent when to use this tool: to find a named calendar before reading its events with get_calendar_events(calendar_id=…). It also provides a concrete troubleshooting action if the account needs reconnecting, linking to the integration URL. This is clear, actionable guidance with an alternative named.

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