Set the fade-in duration in seconds for a chosen media item using its track and item indexes, enabling precise control over how audio enters a REAPER project.
Set the fade-in length of a media item.
Args: length: Fade-in length in seconds.
| Name | Required | Description | Default |
|---|---|---|---|
| length | Yes | ||
| item_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?
With no annotations, the description carries the full disclosure burden. It confirms a mutation of fade-in length but says nothing about overwriting an existing fade, interaction with crossfades, required edit state, undo/reversibility, or whether the item must be identified by index. This is a significant gap for a write tool.
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 purpose sentence is front-loaded and the Args block is terse with no filler. It is efficient, though the Args line merely restates the schema's 'length' property.
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 three-parameter mutation tool with no annotations and no output schema, the definition leaves too much uncovered: two parameters unexplained and no behavioral notes on scope, overwrite semantics, or failure modes.
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% for three required parameters. The description documents only 'length' (seconds), leaving track_index and item_index undefined — an agent cannot tell whether they are 0- or 1-based, or what entity they address. Only one third of the parameters receive any explanation.
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 fade-in length of a media item'), which clearly distinguishes it from sibling mutators like set_item_volume or set_item_mute. It does not, however, name or contrast with its obvious counterpart set_item_fade_out.
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 on when to use this versus set_item_fade_out, set_item_length, or volume/mute setters, and no prerequisites such as whether the item must exist or be selected. The agent must infer usage entirely from the name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.