Click

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

Annotations provide readOnlyHint=false and destructiveHint=false, but the description adds 'Requires Accessibility permission,' which is a crucial behavioral constraint not captured in structured fields. It also implies a mouse input action beyond the annotation hints. No contradiction with annotations.

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 two sentences, front-loaded with the primary action. Each clause provides distinct useful information: action, button options, click count, and permission requirement. No redundant or filler content.

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 4-parameter tool with no output schema, the description covers the core invocation requirements: global coordinates, button choices, click counts, and a permission prerequisite. It does not describe return values, but for an input action this is often standard and not necessary for selection.

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 schema covers 50% of parameters (button and clickCount have descriptions), while x and y lack descriptions. The description compensates by clarifying that x and y are 'a global screen point,' giving meaning to the coordinate pair. This is the key semantic addition beyond schema.

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 starts with a specific verb+resource: 'Click the mouse at a global screen point.' It clearly distinguishes from sibling tools like input_move_mouse or input_scroll. It also specifies button types and click counts, making the purpose 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?

The phrase 'global screen point' establishes the context of coordinate-based clicking. It does not explicitly name alternatives or exclusions, but the sibling tool list makes the distinction clear (e.g., input_drag for dragging, input_scroll for scrolling). This meets the 'clear context, no exclusions' level.

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