check_device_sn

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the lookup/result context (device type and registration status), which is useful, but it does not disclose any behavior beyond what the annotations plus basic lookup semantics imply.

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?

One sentence conveys the action, input, and result with no filler. It is front-loaded with the verb and uses a compact 'to learn X and Y' structure, making it easy for an agent to parse quickly.

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 single-parameter, read-only lookup with annotations and an output schema present, the description is complete. An agent knows what to pass, what to expect conceptually, and that the call is safe and idempotent.

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 100% for the single 'sn' parameter, and the schema already describes it as 'Device serial number.' The description essentially restates this and adds no new parameter-level details, so the baseline of 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 uses a specific verb ('Look up'), identifies the resource ('a serial number'), and states the two concrete outcomes ('device type' and 'whether it is already registered'). This clearly distinguishes it from device-list and device-detail siblings by focusing on SN-based lookup and registration status.

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 makes the invocation context clear: an agent should call this when it has a serial number and needs to know the device type or registration state. It does not explicitly name alternative tools or exclusions, so it stops short of a 5, but the intended usage is unambiguous.

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