disconnect_device

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

With no annotations, the description carries full responsibility for behavioral disclosure. It goes beyond the tool name by explaining that the uiautomator2 session is released, and it clarifies the default-device behavior when serial is omitted. It doesn't mention broader side effects, but the session release is a meaningful and sufficient behavioral detail for this simple tool.

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 two sentences with no filler. The primary action is front-loaded, and the optional serial behavior is presented as a direct, useful follow-up. Every sentence earns its place.

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?

This is a low-complexity tool with one optional parameter and an output schema present. The description covers the core operation, the parameter's default behavior, and the side effect of releasing the uiautomator2 session. Nothing critical is missing for an agent to call this tool correctly.

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?

The schema provides no descriptions for the serial parameter, so the description must compensate. The instruction that omitting serial disconnects the current default device adds real semantics beyond the schema's optional string/null type. It implies that providing a serial targets a specific device, which is enough for a single-parameter tool, though it doesn't state where the serial value comes from.

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 ('Disconnect') with a clear resource ('a device') and adds the behavioral detail of releasing the uiautomator2 session. It distinguishes the action from sibling tools like connect_device and list_devices by specifying the operation on a device-level session.

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 usage context: omitting the serial parameter targets the current default device, which is a practical rule for invocation. It does not explicitly name alternatives or exclusions, but the operation is simple and the context is unambiguous for the common case.

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