Control media playback

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

With no annotations, the description carries the full burden. It transparently describes the behavior as equivalent to pressing a keyboard media key, and notes it affects the current media-owning application. It does not detail edge cases (e.g., no media playing) or permissions, but for a simple key press, the disclosure is adequate.

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?

The description is two sentences, front-loaded with the core action, and contains no redundant information. Every clause adds value: what it sends, its scope, and its effect. Excellent conciseness and structure.

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 simple tool with one parameter and no output schema, the description is complete: it explains the effect, scope, and behavior. It could mention what happens if no media is playing or that there is no return value, but that is not necessary for this kind of fire-and-forget action. The presence of sibling hs_music_control could have been clarified, but overall it is sufficient.

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 schema has 100% coverage (param 'action' has enum and description). The tool description adds some semantics by enumerating effect for play/pause and next/previous but omits 'fast' and 'rewind' from the list. This adds marginal value beyond the schema, but since the schema already defines valid values, the baseline of 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?

The description clearly states the tool sends a system media key and lists specific actions (play/pause, next, previous). It also clarifies it acts on whichever app owns media playback. It's specific and unambiguous, though it doesn't explicitly distinguish itself from the sibling hs_music_control or other media-related tools.

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 description implies usage context (system-wide media keys) and mentions it works with any app, but it does not explicitly state when to use this tool versus alternatives like hs_music_control. There is no mention of exclusions or when not to use. Guidance is implied rather than explicit.

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