select_comp_lane

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

Annotations already indicate idempotent and non-destructive behavior. The description goes beyond this by disclosing error behavior when the track is not in fixed-lane mode or the lane index is out of range. This adds useful context without contradicting the annotations.

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 short and front-loaded with the core action. The error and precondition are clearly stated. The Args section is not bloated, but it is incomplete, which slightly hurts structural quality.

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 two-parameter tool, the description covers the action, precondition, and error cases. However, it omits track_index from the parameter documentation and does not specify what happens on success (e.g., return value or effect). This leaves enough ambiguity that the definition is only minimally adequate.

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 document parameters. It documents lane_index with useful meaning ('0-based', fixed lane to play exclusively), but track_index is entirely absent from the Args section despite being required. The agent is left to infer what track_index refers to, creating a significant gap.

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: 'Make a fixed lane play exclusively on a track'. It is immediately clear this is a lane-based comping operation and is distinct from any sibling tool. The REAPER 7 context further anchors the 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?

The description provides a clear precondition: the track must be in fixed-lane mode, with a pointer to how to enable it. It also states what happens when the precondition is violated or the lane index is out of range. It does not mention alternatives, but no lane-specific sibling tools exist, so exclusions are less critical.

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