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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the bar is lower, and the description still adds real value by clarifying that existing bookings in the window are listed rather than cancelled — the single most important behavioral question for a blocking tool. It leaves open whether the returned list is a preview or a report, and whether overlapping blocks are allowed.

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, front-loaded with the core action and the scope variants, ending with the critical side-effect caveat. The 'Use for holidays, breaks, closures' clause is slightly listy but still carries routing value; nothing else is wasted.

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 7-parameter mutation with no output schema, the definition covers scope modes, staff targeting, and the non-cancellation guarantee. Remaining gaps are small: the 'reason' field is unexplained and the response shape (does it return the affected bookings?) is only hinted at.

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 coverage is 86%, so the schema already documents most parameters. The description goes beyond it by explaining how parameters combine: date+until for multi-day, date+from/to for partial day, staff for a single person. Only 'reason' has no semantics anywhere, a minor gap.

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 and resource ('Stop bookings for a period') and immediately enumerates the two scope modes, whole-day/multi-day and partial-day. An agent can distinguish this from list_bookings or set_booking. It does not name the obvious inverse sibling unblock_time, so differentiation is implied rather than explicit.

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 for holidays, breaks, closures' gives positive when-to-use context, which is more than many definitions offer. However there is no when-not guidance and no reference to alternatives such as unblock_time (to reverse) or update_booking (to move an existing booking).

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