left_mouse_up

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

With no annotations provided, the description fully carries the burden of behavioral disclosure. It explains that the tool releases the button at the current cursor position, requires the frontmost app to be in the allowlist (otherwise error and no action), and is safe to call even if the button is not held.

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 concise (three sentences) and front-loaded with the main purpose. Each sentence adds value: core action, prerequisite, pairing, and safety. No unnecessary words.

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 tool with no parameters or output schema, the description covers all necessary aspects: action, location, prerequisites, pairing, and safety. It is complete for its intended use.

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 has no parameters, so schema coverage is trivially 100%. The description adds no parameter-specific info but provides essential context about the action, which is sufficient given the absence of parameters.

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 clearly states the action (release) and resource (left mouse button) at the current cursor position. It distinguishes from siblings like left_click and left_click_drag by specifying it's a release without additional actions, and pairs with left_mouse_down.

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 explicitly mentions pairing with left_mouse_down, safe to call even if not held, and the prerequisite that the frontmost application must be in the allowlist. It provides clear context for when to use this tool, though it doesn't discuss when not to use it beyond the allowlist requirement.

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