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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered structurally, and the description's 'before applying an edit' corroborates the non-mutating intent. However, it adds nothing about what the preview produces (a diff, conflict list, warnings) or how large an input it can handle, which matters for a tool whose entire value is its output.

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?

A single, front-loaded sentence with no filler: the verb and object lead, and the temporal qualifier comes second. It is efficient, though arguably too terse given the six-parameter surface it has to cover.

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?

With no output schema, the description carries the burden of explaining what a preview returns, and it says nothing about the response shape or how to interpret it. Combined with 0% parameter coverage and nested objects, an agent cannot confidently construct or parse a call from this definition alone.

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% across 6 parameters, including a nested 'settings' object and five untyped/undocumented fields such as 'calendars', 'proposedDirection', and the one-way source calendar IDs. The description only gestures at 'proposed sync settings' in aggregate and gives no meaning, format, or relationship between these parameters, leaving the agent to guess.

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 ('Preview') and resource ('impact of proposed sync settings'), and the phrase 'before applying an edit' frames it as a dry-run rather than a mutation. It does not name the sibling that performs the actual edit (update_sync), so the distinction is implied rather than explicit.

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?

It clearly states the context of use: run this prior to applying an edit, implying it is a pre-flight validation step. There is no explicit when-not or named alternative (e.g., 'to actually persist changes, call update_sync'), so it stops short of full routing guidance.

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