icloud-mcp

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

With no annotations provided, the description carries full burden. It discloses the partial-update/PATCH-like behavior explicitly, which is critical for safe usage. However, it omits other behavioral details like error handling if the event doesn't exist, timezone handling conflicts, or recurrence modification side effects.

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 consists of two efficiently structured sentences with zero waste. The first states purpose immediately; the second provides essential behavioral context. Every sentence earns its place.

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 12-parameter mutation tool with no output schema, the description meets minimum viability by capturing the core operation and partial-update semantics. However, gaps remain regarding return values, error cases, and the specific formats required for complex fields like recurrence rules.

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 low at 25% (only 3 of 12 parameters have descriptions). The description mentions 'provided fields' generally but does not compensate by explaining undocumented parameters like 'recurrence' string format, valid 'status' values, or date-time formats for 'start'/'end'.

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 'Update' and resource 'calendar event', establishing a specific purpose. It distinguishes from create_event by specifying 'existing' event, though it does not explicitly differentiate from siblings like delete_event or get_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 second sentence provides crucial behavioral guidance ('Only provided fields are changed; others are preserved') clarifying partial update semantics. However, it lacks explicit when-to-use guidance versus alternatives like create_event or when to prefer this over delete+create.

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