Add an empty MIDI item to a specified track at a given start time and length, returning the new item index for further editing.
Create an empty MIDI item on a track.
Args: position: Start position in seconds. length: Length in seconds.
Returns: Object with item info including the new item_index.
| Name | Required | Description | Default |
|---|---|---|---|
| length | Yes | ||
| position | 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?
Annotations only include destructiveHint=false, so the description carries some burden. It adds that the item is 'empty' and that the return value is an object with item info including the new item_index. However, it does not disclose behaviors such as whether the item is inserted at the edit cursor, whether it replaces existing items, or any selection or focus side effects. No contradiction with annotations exists.
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 well-structured: a one-sentence purpose, an Args section, and a Returns section. Every line earns its place, with no redundant fluff or repetition of schema fields beyond useful unit clarification.
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 simple creation tool, the description covers the core action, two of three parameters, and the return shape. However, it omits track_index entirely, provides no usage context or alternatives, and does not clarify behavior like insertion position or interaction with existing MIDI items. It is minimally viable but not complete.
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 documents position and length with units ('seconds'), which adds meaning. However, track_index is a required parameter and is completely omitted from the description, leaving the agent to infer its purpose from the phrase 'on a track'. Missing one of three required parameters is a significant gap.
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 ('Create') and resource ('empty MIDI item on a track'), which clearly distinguishes it from siblings like add_midi_note or add_midi_notes_batch that add notes rather than creating an empty item container. The phrase 'empty MIDI item' is precise and 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 guidance is given about when to use this tool versus alternatives such as add_midi_note, add_midi_notes_batch, or clear_midi_item. There are no exclusions, prerequisites, or context about typical workflows. The description only states what it does, not when it should be chosen.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.