focus

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

There are no annotations, so the description carries the behavioral disclosure burden. It does disclose a few non-obvious traits: coordinate-based focus, no text entry, and a 90-second timeout. However, it does not explain side effects, whether the action is effectively a tap/click, prerequisites such as element visibility, or what a successful invocation returns.

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?

Three short sentences, each earning its place: the first defines the core action, the second gives routing guidance, and the third states the timeout. The description is front-loaded with the most important information and contains no redundant filler.

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 low-complexity command with only two required parameters, the description covers the core invocation context: coordinates, non-text behavior, semantic-preference guidance, and timeout. It omits details about return values and failure behavior, but no output schema exists and the tool is simple enough that the description is reasonably complete.

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 input schema already documents all 18 parameters with 100% coverage, including x and y coordinates. The description adds only the implicit context that coordinates are explicit screen coordinates. Since the schema carries the parameter meaning, the description does not need to compensate further.

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, 'Move input focus to explicit screen coordinates', with a clear resource and mechanism. The clause 'without entering text' directly distinguishes it from text-input siblings like type and fill. It is specific enough for an agent to know what the tool does even without inspecting the schema.

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 provides clear usage context: prefer semantic interactions when a snapshot ref or selector is available, and use type or fill after focusing. This gives the agent direction on when not to use the tool. It stops short of naming every alternative sibling, but the guidance is actionable and useful.

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