Set the source channels for a send in REAPER, specifying mono or stereo routing from a track to its destination.
Set the source channels for a send.
Args: track_index: Source track index (0-based). src_chan: Source channel (-1=none, 0=stereo 1-2, 1024+n=mono from channel n).
| Name | Required | Description | Default |
|---|---|---|---|
| src_chan | Yes | ||
| send_index | Yes | ||
| track_index | Yes |
Changes observed during successful MCP inspections.
v1.7.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The only annotation is destructiveHint=false, which the description does not contradict, but it adds no behavioral context beyond that. It does not explain side effects, prerequisites (e.g., send must exist), or any failure modes. Given the annotation covers only destructiveness, the description should still disclose other behavioral traits but does not.
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 purpose. The argument list is clearly formatted and adds necessary details without fluff. It is appropriately concise.
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 3-parameter tool with no output schema, the description should fully document all parameters and any prerequisites. It fails to explain send_index, and there is no mention of whether the send must already exist or how errors are handled. This is inadequate for an agent to use the tool correctly.
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 compensate. It explains track_index (0-based) and src_chan (with encoding details), but it completely omits any explanation of send_index, which is a required parameter. It provides partial value but 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 states a specific verb ('Set') and resource ('source channels for a send'), which clearly distinguishes it from the sibling tool set_send_dest_channels. It is not vague or tautological.
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?
No guidance is provided on when to use this tool versus alternatives. The description does not mention set_send_dest_channels or any conditions for selecting this tool. The agent is left without direction on when this is the appropriate choice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.