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

With annotations providing readOnlyHint=false, destructiveHint=false, and openWorldHint=true, the description adds value by specifying that only 'explicit fields' are updated, implying partial updates and not destructive behavior. It also instructs to 'pass only changes requested by the user,' which is behavioral context not in annotations. No contradictions found.

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 concise: two sentences, front-loading the core action and key guideline. It avoids redundancy with the schema but also omits some potentially useful info like example updates. However, it is efficient and well-structured for its purpose.

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 complexity (6 parameters, mutation, no output schema), the description provides essential context: resolve calendar_id first, pass only changes, and rely on schema for param details. It could mention what fields are updatable or consequences, but the schema covers field details. Missing return info is minor since no output schema exists, but the tool's function is clear.

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 description coverage is 67%, meaning most parameters have descriptions, including important guidance on account_id and calendar_id. The description reinforces that calendar_id must be resolved and only changes passed, which adds value beyond the schema. For parameters without descriptions like name and description, the description's general context compensates reasonably.

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 states 'Update explicit fields on an existing calendar,' which is a specific verb and resource. It clearly indicates this tool is for modifying a calendar, distinguishing it from sibling tools like calendar_create_calendar and calendar_delete_calendar. The description also emphasizes passing only user-requested changes, which adds clarity.

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 provides clear context: resolve calendar_id first and pass only changes requested by the user. It implicitly guides when to use this tool (when updating existing calendars) but does not explicitly state when not to use it or mention alternatives like calendar_update_event. However, the instruction to resolve calendar_id is a strong usage guideline.

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