mouse_down

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

The description discloses significant stateful behavior beyond annotations: the button remains held until released, and the session retains a VM lock requiring vm_unlock. This is exactly the kind of context annotations cannot infer.

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?

Three sentences with no filler: action, mandatory follow-up (release), and VM lock/unlock obligation. Each sentence adds information necessary for correct invocation.

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 side-effecting tool with no output schema, the description covers the essential operational contract: optional movement, hold action, release requirement, and VM lock cleanup. Nothing an agent needs to call this safely or clean up afterward is missing.

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 descriptions already document x/y coordinates, button enum, and vm_name. The description adds meaning by explaining that x/y are optionally moved to before the button press, which is not captured in the schema. Schema coverage is high, so the description complements rather than carries the burden.

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 uses a specific verb and resource ('Hold a mouse button down') and differentiates itself from sibling tools by noting it optionally moves to coordinates first, which distinguishes it from mouse_click, mouse_up, and mouse_move. An agent can tell exactly what action this performs.

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?

It clearly frames the tool's use for press-and-hold input and gives the important instruction to release later. It does not explicitly name sibling alternatives or exclusions, but the condition is clear enough from the stated behavior.

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