mouse_down

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

With no annotations, the description carries the full burden. It discloses the core behavior (button stays held) but omits the key operational fact that a matching mouse_up is required to release, plus any error/state behavior if invoked repeatedly. Adequate for a simple primitive but not rich.

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?

One front-loaded sentence with no filler; the action and the positional constraint are both stated immediately.

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?

The output schema covers return values and the input schema covers the button enum, so little is missing structurally. However, with no annotations and no mention of the required mouse_up pairing, the description under-specifies the lifecycle of the held button.

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?

One parameter ('button') with an enum and a default, and the description never mentions which button is pressed. The enum values and default are self-describing in the schema, so the description adds no meaning beyond it. Baseline 3 for an essentially self-documenting single parameter.

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?

Clear verb+resource: 'Press and hold a mouse button' with the scope qualifier 'at the current pointer position.' An agent can distinguish it from click (instant press+release) and mouse_up (the release half). It does not explicitly name or route against siblings, but the semantics are 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?

Usage is only implied: 'press and hold' hints that this is the opening half of a drag/selection sequence paired with mouse_up, and 'at the current pointer position' implies the cursor must already be placed (e.g., via mouse_move). No alternatives (click, drag) or when-not conditions are stated.

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