play

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

The description names the core effect—starting playback—while the annotation already communicates non-destructiveness. However, it does not add context such as whether playback resumes from the current play cursor or what happens if playback is already active.

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 a single, front-loaded sentence with no filler. Every word earns its place, and it is easily parsed in one pass.

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 parameterless transport command with a destructiveHint annotation and no output schema, the description is nearly complete. The only gap is the lack of relationship guidance to sibling transport controls, which is already penalized under usage guidelines.

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 tool has zero parameters, so parameter semantics are trivially satisfied. The baseline of 4 applies because there is no parameter information the description could or needs to add.

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 uses a specific verb and resource: 'Start playback in REAPER.' It clearly identifies the action and is instantly distinguishable from sibling tools like pause, stop, record, and toggle_repeat, even without inspecting schemas.

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 provides no guidance on when to use this tool versus alternatives. With siblings such as pause, stop, record, and get_play_state nearby, an agent is not told under what conditions play should be chosen, nor when to avoid it.

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