macOS GUI Control MCP

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the action but doesn't mention side effects (e.g., potential UI changes), permissions needed, or system dependencies. This is inadequate for a tool that interacts with the system at a low level.

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 extremely concise with a single, clear sentence that communicates the core functionality without any wasted words. It's front-loaded and efficiently 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 system-interaction tool with no annotations and no output schema, the description is insufficient. It doesn't cover behavioral aspects like what happens after the click, error conditions, or platform dependencies. The context demands more completeness than provided.

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 description adds no parameter-specific information beyond what the schema already provides (100% coverage). It mentions 'screen coordinates' which aligns with the x and y parameters in the schema, but doesn't explain coordinate systems, units, or valid ranges. Baseline 3 is appropriate given the high schema coverage.

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 ('Left-click') and the target ('at screen coordinates'), providing a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like mouse_right_click or mouse_double_click, which would require 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 description provides no guidance on when to use this tool versus alternatives like mouse_right_click, mouse_double_click, or mouse_move. It lacks any context about appropriate scenarios or exclusions, offering only basic functional information.

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