Switches the active microphone or audio input device by exact name, enabling apps to use a chosen input. Check available device names first with list_audio_devices.
Set the active microphone / audio input device by name. Use list_audio_devices first to see available devices.
| Name | Required | Description | Default |
|---|---|---|---|
| device_name | Yes | Exact name of the input device |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing beyond the action itself. It does not say whether the choice persists across restarts, what happens on an unknown device name, whether it interrupts active playback, or whether any permission is required for a mutation of global audio state.
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, zero waste, with the action front-loaded and the discovery step immediately after. Nothing could be trimmed without losing information.
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 one-parameter setter with a fully documented schema and no output schema, the description covers the action and the discovery prerequisite well. The main residual gap is failure behavior for an invalid or unavailable device name, which an agent would likely want before calling.
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 coverage is 100% and the single parameter's 'Exact name of the input device' description is complete, so the schema does the heavy lifting. The description's 'by name' adds a redundant hint rather than new syntax or format guidance; baseline 3 applies.
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 (Set) and resource (active microphone / audio input device) and pins the identifier type (by name). The 'input' qualifier cleanly separates it from the sibling set_output_device.
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?
Gives an explicit prerequisite workflow: 'Use list_audio_devices first to see available devices,' which routes the agent to the discovery sibling. It does not state when not to use it or what happens if the device is already active, so it falls short of a full 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.