Apply a specific preset to an effect plugin on a track in REAPER. Specify track index, FX index, and preset name to quickly load a saved configuration.
Set the preset of an FX.
Args: preset_name: Preset name.
| Name | Required | Description | Default |
|---|---|---|---|
| fx_index | Yes | ||
| preset_name | 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?
No annotations are provided, so the description carries the full behavioral burden, and it discloses nothing: not whether the write is reversible, whether the preset must already be saved, whether it overwrites current settings, or whether it requires an armed/enabled FX. For a mutation tool with zero annotation coverage this is a significant failure.
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?
It is short, but the 'Args: preset_name: Preset name.' block is pure tautology that consumes half the text without adding information. Front-loading is fine, yet no sentence earns its place beyond the opening clause.
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?
A three-parameter mutation tool with no annotations, no output schema, and 0% parameter coverage requires a description that explains state changes, prerequisites, and indexing. This description supplies none of that, leaving the agent unable to call it correctly without external 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?
Schema description coverage is 0% across three required parameters, so the description must compensate and does not. The only documented parameter is preset_name, described tautologically as 'Preset name', while track_index and fx_index are left completely unexplained (indexing base, master-track conventions, FX slot ordering).
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?
States a specific verb and resource ('Set the preset of an FX'), so the core action is clear. However, it never disambiguates whether the FX belongs to a track, a take, or the master, and the sibling list contains both track_fx_* and take_fx_* families. An agent must guess the scope, which is the main thing a preset-setter description should nail down.
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 when-to-use guidance and no routing to relatives such as get_fx_presets, get_fx_preset, or save_fx_preset. The agent gets no signal about prerequisites (does the preset have to exist? which track/FX indexes are valid?) or about the read/inspect alternatives that would normally precede this call.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.