Press Back

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

With no annotations, the description carries the behavioral burden. It usefully discloses that with the keyboard open, Back closes the keyboard instead of leaving the screen, which is a non-obvious trait. It does not describe the ordinary back-navigation effect, device selection behavior, or error handling, but the disclosed nuance is meaningful.

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 short and the useful side effect is placed in a parenthetical, but the opening phrase largely restates the tool name and title. There is no padding or unnecessary detail, though the wording could be more informative.

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 simple, one-parameter action, the description is minimally viable: the action and one important keyboard behavior are clear, and an output schema presumably explains return values. The gap is the undocumented device parameter, which prevents the description from being fully self-contained.

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 has 0% description coverage and the description never mentions the optional device parameter. An agent cannot tell whether device selects a target device, what null means, or why it is optional, so the description adds no semantic value for the only parameter.

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 concrete action, pressing the Back control, and the parenthetical adds a distinguishing effect (closing the keyboard without leaving the screen), separating it from siblings like press_home and press_enter. It does not explicitly contrast with all navigation siblings, so it stops short of a 5.

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 keyboard-dismissal note implies a useful scenario: if the keyboard is open, pressing Back will close it without navigating away. However, it does not name alternatives or give explicit when-to-use and when-not-to-use guidance, so usage is implied rather than stated.

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