macOS GUI Control MCP

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

No annotations are provided, so the description carries the full burden. 'Scroll in a direction' implies a safe action but doesn't disclose behavioral traits like whether it scrolls the active window, requires focus, has rate limits, or what happens with invalid inputs. It lacks context beyond the basic action.

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 sentence, which is front-loaded but under-specified. While efficient, it could benefit from slightly more detail to clarify scope without becoming verbose.

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?

Given no annotations, no output schema, and low schema coverage, the description is incomplete. It doesn't explain what the tool returns, error conditions, or how it interacts with the system (e.g., scrolling behavior), making it inadequate for a tool with parameters and sibling tools.

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 50%, with 'amount' documented but 'direction' lacking description. The description adds no meaning beyond the schema—it doesn't explain what 'direction' values mean in practice or how 'amount' translates to scroll distance. Baseline 3 is appropriate as schema covers half the 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 'Scroll in a direction' states the basic action but is vague about the resource (mouse scrolling) and lacks specificity compared to siblings like mouse_move or mouse_drag. It distinguishes from non-scrolling siblings but doesn't clarify if it's for windows, pages, or other contexts.

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?

No guidance is provided on when to use this tool versus alternatives. It doesn't mention when scrolling is appropriate compared to mouse movement or keyboard shortcuts, nor does it specify any prerequisites or exclusions, leaving usage unclear.

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