computer_mouse_down

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

With no annotations, the description carries the behavioral disclosure burden. It does disclose the key stateful behavior—the button is pressed and held—which is useful. However, it does not mention that the press persists until a corresponding mouse_up, or any side effects such as how this interacts with dragging.

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, clear seven-word sentence with zero filler. Every word contributes to communicating the operation.

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 stateful input operation with a fully documented schema and an output schema present, the description is nearly complete. It tells the agent the button is pressed and held, and the schema covers optional coordinates and button choice. A minor gap is the lack of explicit guidance about pairing with computer_mouse_up for a full click or drag gesture.

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 description coverage is 100%, so the parameters (x, y, button) are already fully documented. The description adds no new semantic information beyond referring to 'a mouse button,' which matches the 'button' parameter. The baseline of 3 is appropriate because the schema does the heavy lifting.

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 and resource combination: 'Press and hold a mouse button.' This clearly distinguishes the operation from siblings like computer_click, computer_double_click, and computer_mouse_up by emphasizing the sustained press rather than a tap or release.

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 such as computer_click or computer_drag, and no mention of pairing it with computer_mouse_up. The intended usage is only implied by the tool name and the phrase 'press and hold,' not explicitly stated.

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