list_calendars

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

With no annotations provided, the description carries the full burden. It discloses the return structure ('array of calendar objects with id, name, and accountId') and the runtime prerequisite (Outlook running) and error condition. This is solid behavioral disclosure, though it doesn't mention side effects (likely none) or additional details like sort order.

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: the first states the core function, the second gives usage direction, and the third describes the return format and a prerequisite/error condition. No superfluous words.

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 zero-parameter tool with no output schema, the description is complete: it explains what it returns, in what structure, and the one critical environmental requirement. There is no missing information for an agent to invoke and interpret results.

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 tool has zero parameters, so there is no parameter guidance needed. The schema is empty with 100% coverage. The description appropriately focuses on output rather than parameters, which is correct.

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 verb 'List' and resource 'calendar folders configured in Outlook', and distinguishes it from sibling tools like list_folders by specifying 'calendar folders'. It also explains its purpose in the context of other calendar operations, removing ambiguity.

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 says when to use this tool: to 'discover calendar IDs for filtering in list_events or specifying a target calendar in create_event'. It also notes the prerequisite that Outlook must be running and the error behavior. It doesn't address alternatives or when not to use it, but the context is clear.

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