calendar_list_calendars

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description usefully adds the permission scope ('permissions: calendar') and version, but the ambiguous 'write support' phrase sits awkwardly against the readOnly annotation and could confuse the agent.

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?

Extremely short and front-loaded, with the action first and metadata bracketed at the end. The only wasted corpus is the ambiguous 'and write support', but overall it is tight.

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 params, rich annotations, and an output schema, the description covers the essentials. What is missing is routing context relative to the other calendar tools and any clarification of what 'write support' means, which leaves a real gap for an agent choosing between siblings.

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?

Zero parameters with 100% schema coverage, so there is nothing for the description to compensate for; baseline 4 applies. No parameter syntax or format detail is needed.

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 clear verb+resource ('List EventKit calendars'), which is enough to distinguish it from calendar_list_events. However, the trailing phrase 'and write support' is vague and muddies what the tool actually does, leaving the agent unsure whether it merely lists calendars or also performs/reports something write-related.

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?

No guidance on when to use this versus calendar_list_events, calendar_find_free_slots, or any sibling. The 'permissions: calendar' tag hints at a prerequisite but doesn't tell the agent anything about selection context or exclusions.

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