Left Mouse Down

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

The description offers only the vague qualifier 'scoped' beyond the annotations; it does not explain what the scope is, whether the pointer moves to the target first, or that this should be paired with left_mouse_up. DestructiveHint already signals mutation, but the description adds little concrete behavioral context.

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 sentence with no filler, front-loaded with the verb 'Begin'. Its brevity is a trade-off against clarity, but as a concise statement of the core action it is well-structured.

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 tool with a required target that can be an element or coordinate, an optional app_ref, and a return_state option, the single sentence omits how the target is used, when to call the companion left_mouse_up, and what 'scoped' means operationally. The lack of an output schema increases the burden, yet the description does not address it.

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 only 33%, with target and app_ref lacking top-level descriptions. The description does not explain target, its element/coordinate forms, or app_ref, so an agent must rely on nested schema properties. The word 'scoped' provides at best an indirect hint that the target bounds the hold.

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 ('Begin') and resource ('left-button hold'), and the word 'scoped' hints that the hold is bounded, distinguishing it from one-shot clicks like left_click and releases like left_mouse_up. It does not explicitly mention the required target parameter or the pairing requirement, so it is not maximally explicit.

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 left_click, left_click_drag, or left_mouse_up. The description does not mention the expected pairing with left_mouse_up or any conditions that would make a hold preferable to a click or drag.

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