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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond them: results are read live from the calendar, slots are 30-minute Google Meet calls, and availability is bounded to Monday–Friday 10:00–18:00 Istanbul time — all material to interpreting results.

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?

Two sentences, zero filler. The output content and business constraints come first, the usage trigger second — properly front-loaded.

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?

There is no output schema, yet the description conveys the essentials of what comes back (open slots for a defined meeting type, in a defined window) and the timezone/hours frame needed to act on it. It stops short of describing the response shape (slot granularity, date grouping) and any rate limits, which is the remaining gap.

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 100%, so the schema already documents days, from, language and timeZone including defaults and bounds. The description only reinforces the Istanbul timezone default and adds no per-parameter meaning (no format hints, no guidance on combining from + days), so the baseline of 3 applies.

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?

A concrete verb ("Returns") plus a precisely scoped resource ("open slots" for a 30-minute intro video call on Google Meet), with the data source named (his live booking calendar). The distinction from the sibling book_intro_call is implicit but obvious from semantics: this reads slots, that one books 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?

"Use when the user wants to schedule a call" gives a triggering context, but it does not name book_intro_call as the follow-up action or state when not to use this tool. An agent could plausibly read "wants to schedule" as an instruction to book directly, so the routing guidance is implied rather than explicit.

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