List detected screen and audio capture devices, returning their index values for use in recordings. Run first to find the correct screen_index when unsure.
List all available screen and audio capture devices detected by FFmpeg avfoundation. Use the index values when calling start_recording. Run this first if you're unsure which screen_index to use.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the disclosure burden. It reveals the implementation backend (FFmpeg avfoundation) and that the output includes index values usable by start_recording. It does not explicitly state that listing is side-effect-free, though 'List' and the discovery framing imply a read-only operation.
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, each with a distinct job: declare the function, connect the output to start_recording, and provide a when-to-run condition. No filler or repeated schema 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?
The definition is complete for a zero-parameter discovery tool: it states what is listed, the platform, how the results are used, and when to invoke it. Without an output schema, the description still conveys that index values are returned, which is enough for an agent to call and interpret the tool.
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?
The input schema has zero parameters and 100% schema coverage, so the baseline is 4. The description adds no parameter details, which is appropriate because there are no parameters to explain.
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 action ('List') with a clear resource ('all available screen and audio capture devices') and platform context ('FFmpeg avfoundation'). This distinguishes it from list_recordings, which lists recording files, and clarifies the device-discovery role. The instruction to use returned index values in start_recording reinforces the tool's purpose.
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 explicit sequential guidance: run first when unsure which screen_index to use, and use the returned index values when calling start_recording. It doesn't name alternatives or exclusions, but the sibling tools are clearly different lifecycle/listing operations, so the stated guidance is sufficient.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.