press_back

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It says nothing about whether this requires a connected device, what happens if no back stack exists, whether it blocks, or what the response contains. The output schema exists, so return values need not be explained, but operational context is missing.

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 a single, front-loaded sentence with zero waste. It is appropriately sized for the simplicity of the operation, though it borders on being too terse to be useful.

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 device-control action in a large sibling set, the description is inadequate. It does not say when to use it over press_home or keyevent, does not mention the device serial parameter, and provides no behavioral context. The existence of an output schema covers return values, but the description remains too thin for an agent to invoke confidently without external knowledge.

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?

There is only 1 parameter (serial) and it is optional with schema description coverage at 0%. With 0 required params and a single nullable serial parameter, the baseline is 4. The description does not mention the serial parameter, but for such a simple optional target selector, the schema's presence is largely self-explanatory and no compensating detail is strictly required.

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 states a specific action (press the BACK button), which is clear enough as a hardware key simulation. However, it is a near-tautology of the tool name 'press_back' and does not distinguish itself from sibling navigation tools like press_home, press_recents, or keyevent. It communicates the verb+resource but adds no scope or differentiation.

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?

There is no guidance on when to use this tool versus alternatives. An agent working with press_home, press_recents, keyevent, or tap_element gets no routing information. For a one-line description, usage context is entirely absent.

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