Create a named region between two time positions in a REAPER project, returning its index for later reference.
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?
No annotations provided, so the description carries full burden. It does not mention mutation, permissions, whether the operation is reversible, or side effects. It only states the return object with region index, which is minimal. For a mutation tool with no annotations, this is a significant gap.
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 brief and front-loaded with the purpose. The Args and Returns sections are structured and easy to parse. It could be slightly more concise by integrating parameters into a sentence, but overall it's efficient.
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 4-parameter mutation tool with no annotations and no output schema, the description is adequate but incomplete. It does not cover behavioral aspects like side effects, error conditions, or return structure beyond 'region index'. The parameter semantics are documented, which helps, but broader context is missing.
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 does document all four parameters: start and end in seconds, name, and color with default explanation. This adds necessary semantic meaning beyond the schema's bare types. However, it lacks constraints (e.g., valid ranges for start/end, color encoding).
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?
Description clearly states 'Add a region', a specific verb+resource. Siblings like add_marker, get_regions, delete_region exist, but the description doesn't explicitly differentiate or reference them. A 4 is appropriate: clear but no sibling differentiation.
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 or when-not-to-use guidance. It does not mention alternatives like add_marker or conditions under which this tool should be used. The description provides only the basic purpose, leaving usage context implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.