select_comp_lane

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

Annotations already declare readOnlyHint=false and idempotentHint=true, and the description adds useful behavioral context: fixed-lane mode requirement and explicit error behavior. It does not fully explain the effect on other lanes or undo semantics, so it is not maximally transparent.

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, front-loaded, and well-structured: purpose first, prerequisite/error behavior second, and the lane_index argument last. Every sentence adds useful information without waste.

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 mutating lane-selection tool with annotations and no output schema, the definition covers the key operational prerequisite and error behavior. However, it omits the required track_index parameter meaning and does not describe the effect on other lanes beyond the word 'exclusively'.

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% for two required parameters, so the description must compensate. It documents lane_index well (0-based, fixed lane index) but omits track_index entirely, leaving half the parameters unexplained.

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 states a specific verb and resource: making a fixed lane play exclusively on a track in REAPER 7 lane-based comping. It clearly distinguishes this lane-level operation from take-level sibling tools such as set_active_take and crop_to_active_take.

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?

It provides a clear prerequisite: the track must be in fixed-lane mode, and it states the error behavior when that condition or the lane index is invalid. It does not name alternative tools or give broader when-not guidance, so it falls short of a 5.

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