update_event

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

There are no annotations, so the description must carry the transparency burden. It does disclose a key behavior: fields not included retain existing values, indicating a partial update. It also provides format details for start/end/timeZone. However, it does not mention permissions, error handling, idempotency, or what happens when setting a field to null, leaving significant behavioral gaps.

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 well-structured with a concise introductory sentence followed by a clean Args block. Every parameter is listed with its format and optionality. The repetition of 'Defaults to None' is minor and acceptable for readability. It is appropriately sized and 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 7-parameter mutation tool with no output schema or annotations, the description covers the core update semantics and parameter formats but lacks important context: return value, error behavior, null clearing, and prerequisites. It is adequate for basic use but not comprehensive for an agent handling edge cases or unexpected scenarios.

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 0%, so the description must compensate. The Args block provides meaningful detail beyond the schema: ISO 8601 format examples, timezone database naming, and default behavior (None). This helps an agent construct valid calls, though some inter-parameter details (e.g., timeZone applicability) are missing.

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 opens with a specific verb and resource: 'Updates an event by replacing specified fields with new values.' The partial-update behavior is explicitly stated, which distinguishes this from create and delete siblings. It is clear that this tool modifies an existing event.

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 context for using this tool is clear: it updates an existing event, as opposed to list, create, or delete. However, it does not explicitly mention alternatives or provide 'when not to use' guidance. The sibling tool names are not referenced in the description, so the guidance is implicit rather than explicit.

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