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

The readOnlyHint/idempotentHint annotations already declare the safety profile, and the description adds two pieces of genuinely new context: the required `calendar:read` scope and the note that human-authored text arrives in `untrusted_fields` and must not be treated as instructions. It does not explain what "free" is derived from (busy blocks, feeds, connected calendars) or the shape of the result, which is the remaining behavioral blind spot.

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?

Three short sentences, each doing distinct work: purpose, prerequisite scope, and an injection-safety warning. Purpose is front-loaded and there is no filler.

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 should clarify what a result looks like (a boolean? busy intervals?) and what sources count toward availability, neither of which it does. The auth and untrusted-field notes partially compensate, but the return semantics remain undefined.

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 schema supplies only `start` (required) and `end` (optional) as untyped-except-string fields. The description says nothing about expected format (ISO 8601?), timezone handling, or whether `end` defaults to a point-in-time check, leaving both parameters effectively undocumented.

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?

"Check whether I am free" names a specific verb (check availability) and scope (the authenticated user's own schedule), which is clear enough to act on. It never distinguishes itself from adjacent calendar-reading siblings such as get_calendar_days, list_calendar_events, or get_calendar_block, so an agent must guess among them.

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 description offers no when-to-use, when-not-to-use, or alternative-tool guidance at all. Given a sibling list crowded with calendar tools, the absence of any routing signal is a real gap.

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