computer_hold_keyHold a single keyboard key for a set duration before releasing, useful for modifier-assisted actions such as Shift-click range selection.
Hold a key for duration seconds then release (e.g. Shift for click-select ranges). One chord only — no '+' combos.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | ||
| duration | No |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden. It usefully discloses the auto-release semantics (hold then release after the duration) and the single-key limitation, but says nothing about focus requirements, whether the call blocks for the duration, or what happens if the key is invalid.
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?
Two short sentences, both front-loaded with the core behavior and the key constraint. Nothing is wasted and the most important restriction is stated last for emphasis.
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?
An output schema exists, so return values need not be explained, and the tool has only two simple parameters. The description covers the essential behavior; only the key-name format and focus/blocking behavior for the hold are left unstated.
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 — and it does: it specifies that duration is in seconds and that key accepts only a single key, not a '+'-joined combo. It still omits the expected key-name format (e.g. 'Shift' vs 'shift' vs keycode), which is the main remaining gap.
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 key for duration seconds then release') with an example use case. The clause 'One chord only — no '+' combos' implicitly differentiates it from the sibling computer_key tool, though it never names that sibling directly.
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 Shift-for-drag-selection example gives a concrete scenario, and the no-combos note hints the agent should use a different tool for chords. However, no alternative tool is named and there is no explicit when-not guidance, leaving the agent to infer that computer_key handles combinations.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.