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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds valuable context by noting that activation sets the next run from the schedule, and that depending on configuration the loop can change bookkeeping records or email invoice reminders to external recipients. It also mentions preview mode requiring approval, which is useful behavioral context. While it doesn't detail side effects like exactly what records change or email content, the annotations plus description sufficiently convey the risk profile.

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?

The description is reasonably concise at about four sentences, with the core action front-loaded in the first sentence. Later sentences add relevant context about schedule, effects, and approval requirements. It is not overly verbose, though the last sentence about the Caribooks portal is somewhat tangential and could be trimmed without losing essential meaning.

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 tool with one parameter, no output schema, and clear annotations, the description covers the essential context: what it does, when it's appropriate, the approval requirement, and potential side effects. It doesn't describe the return value, but without an output schema, that's less critical. The main gap is that it doesn't explicitly state prerequisites like 'loop must be paused' (though implied by 'existing paused') or what happens if the loop is already active, but overall it's fairly complete.

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 the single parameter loop_id is well described in the schema itself ('The loop's id, as create_task and list_loops show it.'). The description doesn't add much beyond the schema, but it does contextualize that the loop must be paused and existing, which implies the ID refers to an existing paused loop. Since the schema already handles the parameter description well, a baseline 3 is appropriate.

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 clearly states the tool activates an existing paused bookkeeping loop by id after user approval, which is a specific verb-resource pair. It mentions setting the next run from its schedule and distinguishes between preview mode requiring approval and normal activation, but doesn't explicitly differentiate it from sibling tools like 'list_loops' or 'create_task' that might be related to loop management.

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 description gives clear context for when to use this tool: to activate a paused loop after user approval, and mentions preview mode requires approval of proposed actions. However, it doesn't explicitly state when not to use it or name alternative tools for managing loops (e.g., if the user wants to modify a loop instead of activating it), though the context implies activation is the specific purpose.

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