Control media playback on a Windows PC by sending media key presses to play or pause, skip tracks, and raise, lower, or mute volume in apps like VLC or browser players.
Aperta uma tecla de mídia do Windows: controla o que estiver tocando no PC (VLC, SoundCloud no navegador…).
| Name | Required | Description | Default |
|---|---|---|---|
| acao | Yes |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=false. The description adds useful context beyond them by revealing the underlying mechanism (a simulated Windows media key) and that it targets whatever is currently playing, which explains the non-idempotency. It does not say what happens when nothing is playing, which app wins when multiple media sessions exist, or whether there is a return value.
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?
A single front-loaded sentence with no filler: mechanism first, effect second, examples last. Slightly denser than necessary, but every clause contributes meaning.
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 enum tool with no output schema, the description covers what it does and its side effects adequately. The remaining gap is outcome reporting — an agent cannot tell whether the call returns the new playback state or just an acknowledgement, nor how failure (no active media session) surfaces.
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 carry the parameter burden; it partially does by framing the tool as pressing a media key, which makes the enum values (tocar_pausar, proxima, anterior, volume_mais, volume_menos, mudo) largely self-interpreting. However, it does not map or explain any individual enum value, so the compensation is incomplete.
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 names a specific mechanism ('Aperta uma tecla de mídia do Windows') and the resource it affects ('o que estiver tocando no PC'), with concrete examples (VLC, SoundCloud no navegador). It is clearly distinguishable from siblings like midia_status or tocar_pasta, though it never explicitly contrasts itself with them.
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?
Usage is only implied: an agent can infer this is the tool for play/pause/skip/volume control, but there is no explicit when-to-use versus midia_status (which presumably reports state) or tocar_pasta/abrir_soundcloud (which start playback). No prerequisites or exclusions are stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.