Manage effects on any REAPER track, including the master, by listing, adding, adjusting parameters, deleting, bypassing, moving, and applying presets.
Track FX. action: list | add | params | set | delete | bypass | move | preset. track_index -1 is the master. set value is 0..1 (REAPER normalized).
| Name | Required | Description | Default |
|---|---|---|---|
| param | No | ||
| value | No | ||
| action | Yes | ||
| preset | No | ||
| enabled | No | ||
| fx_name | No | ||
| fx_index | No | ||
| dest_index | No | ||
| track_index | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full transparency burden. It discloses valuable semantics such as -1 representing the master track and the normalized 0..1 range for set, but it does not explain side effects of delete, bypass, or add, or whether operations are destructive. This is partial transparency, not a full behavioral profile.
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 compact and front-loaded: the action list appears first, followed by the two most important numeric semantics. Apart from the slightly redundant 'Track FX.' opener, every sentence contributes usable information.
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 tool with 8 actions, 9 parameters, no output schema, and no annotations, the description is materially incomplete. It lacks per-action parameter requirements, return behavior for list/params, and semantics for dest_index and preset, so an agent would need trial and error or outside knowledge.
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 0% description coverage and 9 parameters; the description only adds meaning for action, track_index (-1 = master), and value (REAPER normalized 0..1). It leaves param, preset, enabled, fx_name, fx_index, and dest_index undefined, and never maps which parameters belong to each action, so an agent cannot reliably construct a call.
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 identifies the resource (track FX) and enumerates eight concrete actions, so an agent can tell this tool is for manipulating effects rather than transport, items, or sends. It is terse and the opening phrase borders on restating the tool name, but the action list gives it real definition.
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?
There is no explicit guidance about when to use fx versus sibling tools like send, track, or item; the need is only implied by the resource name and action list. The description does provide two operational rules (track_index -1 means master, set values are normalized 0..1), but no exclusions or alternative routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.