mouse_down

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

With no annotations, the description carries the full behavioral burden. It never says the button stays latched in a down state until a matching mouse_up/mouse_release, nor what happens if that follow-up never comes (stuck button for later actions) — the single most important behavioral fact for this tool.

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 short sentence, front-loaded with the action and the intent, with no filler. Its brevity is efficient rather than padded, though it borders on under-specification.

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?

A simple one-parameter tool with no output schema, so little is required. Still, for a state-mutating input device tool with zero annotation coverage, the missing latch/release contract leaves a real gap for an agent orchestrating a drag sequence.

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 compensate, but it only says 'a mouse button' without naming the left/right/middle enum. The enum values are self-explanatory, keeping this at a baseline 3 rather than lower.

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?

States a specific verb and resource ('Hold a mouse button down') plus the intent ('start a drag'), which clearly separates it from mouse_click and mouse_scroll. It does not, however, distinguish itself from mouse_up or mouse_release, siblings whose relationship to mouse_down is exactly what an agent needs to resolve.

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 parenthetical '(start a drag)' implies the scenario, but there is no explicit guidance on when to use this versus mouse_click (which likely does press+release) or which release tool to pair it with. Usage must be inferred.

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