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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the description is not needed for the safety profile. It nevertheless adds genuine side-effect detail the annotations cannot express: it triggers the `uptime.maintenance_window.cancelled` alert rules and resumes the monitors the window had paused. It also names the terminal-state failure mode, so an agent knows the call will be rejected on already-cancelled windows.

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?

Purpose is front-loaded in a single dense sentence with no filler, and every clause carries information (state scope, side effects, precondition). The second clause is grammatically tangled — "trigger the ... alert rules, the monitors it paused are resumed" — which slightly slows parsing of the effect list.

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 two-parameter mutation with full schema coverage, annotations, and no output schema, the description covers the essentials: what it acts on, what it triggers, what it resumes, and when it fails. Return shape and permission requirements are the only unaddressed items, and the former is a minor gap given no output schema exists.

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% and both parameters are documented in the schema, including the pointer to `whoami` for project_id. The description only restates "by ID" and adds no format, constraint, or lookup guidance beyond what the schema supplies, 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?

The description gives a specific verb and resource ("Cancel a scheduled or in-progress maintenance window by ID") and names the state scope, so the operation is unmistakable. It does not, however, distinguish itself from nearby siblings such as `complete_maintenance_window` or `delete_maintenance_window`, leaving the agent to infer the boundary between the three.

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?

"Cancel a scheduled or in-progress maintenance window" plus "Completed or already cancelled maintenance windows cannot be cancelled" gives a clear applicability condition and an explicit when-not rule. The gap is that it never points to the alternatives (delete vs. complete) when the cancellation precondition fails.

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