calendar_list

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

The readOnlyHint annotation already indicates a safe read operation. The description adds that it lists 'all' calendars, providing scope beyond the annotation. However, it does not disclose additional behavioral traits such as sorting, pagination, or authorization requirements, which are not critical for this simple listing tool.

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 a single concise sentence that is front-loaded and contains no redundant information. It fully communicates the tool's purpose in minimal 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?

Given the tool's minimal complexity, read-only annotation, and absence of parameters, the description is complete. While there is no output schema, 'Lists all of the user's calendars' sufficiently conveys the expected return for a list operation, and no additional context is necessary.

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 parameter semantics are trivially covered (100% schema coverage). The description does not need to explain parameters, and a baseline of 4 is appropriate per guidelines for tools with no parameters.

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 ('Lists') and resource ('all of the user's calendars'), clearly distinguishing this tool from sibling calendar tools that operate on events or individual calendars. It unambiguously states the tool's primary function.

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 implies use when needing to retrieve all calendars, but it does not explicitly state when to use it over alternatives or any exclusions. Given the simplicity of the tool and clear sibling context, the usage is implied rather than articulated.

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