app_click

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

With no annotations, the description carries the full burden and does well: it discloses the mechanism ('Uses PostMessage with automatic child window targeting'), the coordinate system ('screenshot pixels'), and case-insensitive window matching. It does not cover side effects like focus changes or failure modes, but the primary behavior is well explained.

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 structured with a clear intro, a usage hint, a mechanism note, and an Args list. It front-loads the purpose and each section earns its place. Slightly verbose but still focused – the workflow sentence is necessary for correct use.

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 moderate parameter count (5) and presence of output schema, the description covers the essential call context: coordinate acquisition via screenshot, window targeting, and each argument's meaning. It does not describe error behavior or prerequisites like visible windows, but for a click tool this is sufficient.

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 0%, so the description must fully document parameters. It does: window_title (full or partial, case-insensitive), x/y (screenshot pixels), button (left/right with default), double_click (boolean meaning). This adds meaningful semantics that the schema fails to convey.

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 states a specific action ('Click') on a specific resource ('Windows application window at the given coordinates'), and distinguishes it from related tools like screenshot_app (captures the screen for coordinate reference) and adb_tap (Android-specific). The verb+resource+method is explicit and unambiguous.

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?

Provides explicit workflow guidance: 'take a screenshot_app first to identify where to click, then use those pixel coordinates here.' This tells the agent when and how to use the tool. It does not list explicit 'when not to use' or alternatives, but the context is clear enough for typical use.

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