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

With no annotations, the description carries the full disclosure burden, yet it only implies a state-changing navigation. It does not say what happens when there is no back stack to pop (error, no-op, or app exit), whether the action affects only the given session, or whether any permissions or valid-session preconditions apply.

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?

A single five-word sentence with the action front-loaded and no filler. It is efficient, though the extreme brevity borders on under-specification for a stateful device action.

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?

The tool has one required parameter, no output schema, and no annotations, so the description is the only source of behavioral detail; it provides none. An agent cannot tell how failures, empty history, or session scoping behave, which is material for a navigation command in a device-control suite.

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%, and the single session parameter is documented as coming from open_app, so the schema already does the work. The description adds no further meaning about the parameter, which meets the baseline 3 for high-coverage schemas.

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?

'Go back one screen' states a concrete navigation action with a clear verb and unit of navigation, which is immediately distinguishable from sibling device actions like tap, scroll, and type. It stops short of naming or contrasting an alternative, but the action itself is unambiguous.

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 no conditions for when to use this instead of alternatives such as tapping an in-app back button or reopening the app via open_app. There is also no mention of prerequisites, such as a prior open_app call or an existing navigation history.

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