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

Goes well beyond annotations (destructiveHint, idempotentHint, openWorldHint) by disclosing that omitted fields stay unchanged, that conflict_calendar_ids replaces the full list, that the destination must be writable and is always in conflict checks, and that existing meetings are not moved. This is exactly the mutation semantics an agent needs.

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?

Front-loaded and well organized into behavior, when-to-use, and example. The 'When to use' sentence largely restates the opening line ('which connected calendars block your time and which writable calendar receives bookings'), which is mild redundancy, but the rest 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?

An output schema exists so return values need not be explained, and the description still covers the optimistic-concurrency prerequisite (read the version first, re-read after conflict) and mutation semantics. Nothing material is missing for an agent to call this correctly.

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 100% so the baseline is 3, but the description adds real semantics beyond the schema: omitted fields are preserved, conflict_calendar_ids is a full replacement rather than a merge, and the destination is implicitly always included. It does not add syntax detail beyond this, so it exceeds but does not max the baseline.

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?

States a specific verb and resource ('Choose which of your connected calendars block availability and where new meetings are created'), and distinguishes itself from the sibling get_scheduling_settings by naming it as the read path for calendar IDs. An agent can tell what this does and how it differs from related tools without opening the schema.

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?

Has an explicit 'When to use' block, names the prerequisite read (get_scheduling_settings for IDs and version), states scope ('selections apply across your workspaces'), and includes a when-not constraint ('Does not connect accounts or grant permissions'). Covers both selection and destination use cases with an example.

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