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 of behavioral disclosure. 'Resize' implies a mutation (changing window size), but the description doesn't specify whether this requires permissions, if it's reversible, what happens with invalid inputs (e.g., negative dimensions), or potential side effects (e.g., window snapping or constraints). This leaves critical behavioral traits unaddressed.

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 ('Resize application window'), which is front-loaded and wastes no words. For a simple tool, this brevity is appropriate, though it may sacrifice clarity. Every word earns its place by directly stating the core action.

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 the complexity (a mutation tool with 3 parameters), no annotations, no output schema, and 0% schema description coverage, the description is incomplete. It doesn't explain what 'resize' entails (e.g., immediate effect, success/failure indicators), parameter details, or how it interacts with the system. This leaves significant gaps for an agent to understand and use the tool effectively.

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 3 parameters (app_name, width, height) with 0% description coverage, meaning none are documented in the schema. The description 'Resize application window' only implies the parameters indirectly (e.g., app_name for the window, width/height for size) but adds no explicit meaning, units (e.g., pixels), or constraints (e.g., valid ranges). This fails to compensate for the schema's lack of documentation.

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 'Resize application window' clearly states the verb (resize) and resource (application window), making the basic purpose understandable. However, it lacks specificity about what 'application window' refers to (e.g., a specific app window vs. all windows) and doesn't differentiate from sibling tools like 'window_move' or 'window_focus', which leaves room for ambiguity.

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. It doesn't mention prerequisites (e.g., needing the app to be open), exclusions (e.g., not working with certain apps), or how it relates to siblings like 'window_move' (which might handle positioning) or 'window_list' (which could list windows). This absence of context makes it harder for an agent to choose correctly.

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