Define a named time-range region in REAPER by setting start and end seconds; include optional color and return the new region index.
Add a region.
Args: start: Start position in seconds. end: End position in seconds. name: Region name. color: Region color (0 = default).
Returns: Object with region index.
| Name | Required | Description | Default |
|---|---|---|---|
| end | Yes | ||
| name | No | ||
| color | No | ||
| start | Yes |
Changes observed during successful MCP inspections.
v1.7.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With only destructiveHint:false in annotations, the description carries the burden for behavioral disclosure. It only states that a region is added and returns an object with a region index, without mentioning side effects, validation rules, or interaction with project state. This is minimal.
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 a compact docstring with a one-line purpose, four parameter lines, and a one-line return. Every sentence earns its place and there is no fluff.
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 add operation the description covers the essentials, but it lacks context about project requirements, error behavior, and a clearer return structure than 'Object with region index.' With no output schema, a bit more detail would make it fully self-sufficient.
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 0%, so the description fully compensates by defining start and end in seconds, name as a region name, and color with its default. This adds meaning beyond the raw schema types, though it omits constraints like start < end or name uniqueness.
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 opens with 'Add a region,' a specific verb and resource. Among siblings like delete_region, get_regions, and add_marker, this clearly identifies the tool as the creating operation for regions.
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 on when to use this tool versus alternatives such as add_marker, render_region, or go_to_region. There are no prerequisites, exclusions, or context hints beyond the obvious 'add a region'.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.