Splits a MIDI item in two at a chosen bar and beat in REAPER, returning the IDs of both resulting sections.
Splits an item in two at a bar/beat; returns both halves' ids.
| Name | Required | Description | Default |
|---|---|---|---|
| at_bar | Yes | ||
| at_beat | No | Beat within the bar, 1-based (default 1) | |
| item_id | Yes | MIDI item id from create_midi_item/get_track_details, or "selected" |
Changes observed during successful MCP inspections.
v0.19.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose the key mutation effect (one item becomes two) and the return value (both halves' ids). However, it omits what happens to MIDI notes or automation spanning the split point, whether the split is undoable, and any permission requirements.
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?
A single front-loaded sentence with the operation and its result, no filler. It is efficient, though its brevity contributes to the spec gaps noted elsewhere rather than being purely a strength.
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-param mutation tool with no annotations and no output schema, the description covers the basic operation and the return shape, which is the minimum viable. It does not address note-handling behavior at the cut point or the semantics of the undocumented at_bar parameter, leaving real gaps.
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 coverage is 67%: at_beat and item_id are documented in the schema, while at_bar has no description. The description's 'at a bar/beat' phrasing loosely maps to at_bar/at_beat but adds no format or defaulting detail (e.g., 1-based bar, default beat 1) beyond the schema, so the baseline 3 holds.
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 (splits) and resource (item) with the operation's locus (at a bar/beat), which clearly distinguishes it from siblings like delete_item, duplicate_item, and edit_item. It stops short of naming those siblings explicitly, but the purpose is unambiguous.
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, when-not-to-use, or alternative guidance is given. The agent must infer that this is the tool for cutting an item rather than duplicating (duplicate_item) or modifying it (edit_item); nothing routes it explicitly.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.