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

Annotations already declare write/idempotent/non-destructive, but the description adds real behavioral context beyond them: it keeps the alarm and all its contents, deleting is permanent and separate, and for a joined alarm it only toggles ringing for that user. It also discloses the return ('the alarm as it is now'). This is exactly the extra context annotations cannot carry.

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?

Four short sentences, each carrying distinct information (scope, preservation, scope of access, return). The core action is front-loaded and there is no filler.

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 toggle with full schema coverage and confirming annotations, the description supplies everything an agent needs: what changes, what is preserved, who it applies to, and the return shape. Nothing material is missing.

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%, so both parameters ('id' and 'on') are already fully documented in the schema. The description adds no syntax or format detail beyond restating the on/off toggle, 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 verb+resource ('Turns an alarm on or off') and immediately narrows scope ('without changing anything else about it'), which cleanly distinguishes it from update_alarm and delete_alarm. An agent can tell what it does 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?

Gives clear usage context by noting it works on both owned and joined alarms, and that deleting is 'permanent and separate' – implicitly steering away from delete_alarm. It stops short of explicitly naming the alternative tools or stating when-not-to-use conditions, so it is a strong 4 rather than a 5.

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