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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description still adds two non-obvious facts beyond annotations: recorded hits are preserved and remain readable, and the operation is gated behind a Pro plan. That retention/auth context is exactly the kind of value the description should add.

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 action, then the retention consequence, then the prerequisite. No filler and each sentence carries distinct information.

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?

An output schema exists, so return-value detail is not needed, and the description covers the key concerns for a destructive one-param operation: what it does, what survives, and the plan prerequisite. Only the token's origin/format is left unaddressed.

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 0% for the single 'token' parameter, so the description must carry the burden. It does say the monitor is identified 'by its token', which confirms the parameter's role, but gives no format, source, or example of where that token comes from (e.g., list_monitors). Adequate but incomplete.

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 ('Cancel an active or paused monitor') and specifies the identifying key ('by its token'). It does not explicitly name or contrast with siblings like list_monitors or check_monitor, but the action is distinctive enough that an agent can place it without opening the schema.

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 phrase 'active or paused monitor' implies the valid state conditions for calling it, and 'Requires Keeploop Pro' is a real prerequisite. However, no alternative tool is named and no when-not-to-use guidance is given (e.g., what to do for an already-cancelled or completed monitor).

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