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

Beyond the annotations (readOnly=false, destructive=false) it discloses that the Event has no guests, that nobody is emailed, that it runs without a confirmation prompt, that it is reversible via delete_event, and that it requires a Cotlet API key with app access. This is substantial behavioral context an agent cannot infer from the structured fields.

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-loads the core action well, but repeats itself: 'customers cannot book that time' appears twice and 'adds no guests' is stated twice, padding what could be a tighter block. Most sentences earn their place, but the redundancy costs it.

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?

For a mutation tool with no output schema, the description covers purpose, side effects (no emails, no confirmation), reversibility, the non-overlapping alternative (Time Off), and auth requirements. An agent has everything needed to invoke it 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 description coverage is 100% (notes, start in ISO 8601 with time zone, staff_id defaulting to yours, duration within one day), so the schema carries the parameter burden. The description adds no parameter-level detail beyond the schema, so the baseline 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?

States a specific action and outcome: adding an Event to the calendar so customers cannot book that time on the Booking Page. It distinguishes itself from delete_event (the inverse) and from Time Off, so an agent can tell it apart from siblings without opening schemas.

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?

Gives a clear when-to-use (blocks within a day) and a when-not-to-use (longer absences belong to Time Off, which this tool does not change), plus names delete_event for removal. It stops short of routing against sibling booking tools like create_appointment, but the context is explicit.

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