free_busy

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real value beyond that: intervals are merged, no event details are returned, and it 'needs EventKit' (a platform/permission precondition the schema does not express).

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 with the core purpose, then parameter notes, then return shape and precondition — every clause earns its place. Slightly dense/compressed prose costs it the top mark.

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?

Covers inputs, output shape ('{busy: [...], free: [...]} of {start, end}'), what is deliberately omitted ('no event details'), and the EventKit dependency. Nothing an agent needs to invoke it correctly is missing despite the output schema existing.

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 carries the full burden and does: `start`/`end` are ISO-8601 naive local datetimes with a concrete example, and `calendars` is defined as optional Pointer ids sourced from the `calendars` tool, defaulting to all. That is meaning the schema alone cannot convey.

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+resource ('Availability in a window') and immediately names the two outputs it computes ('merged busy intervals + free gaps'), which distinguishes it from sibling `events` (raw event listing). An agent can tell exactly what it produces 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?

It explains the scoping option ('calendars optional Pointer ids... else all') and the read-only nature, which implies 'use this when you want free/busy rather than event details.' But it never explicitly says when to prefer this over `events` or names the alternative.

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