REAPER MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Discloses UI visibility requirement beyond schema, but lacks details on side effects (multiple points), error behavior if envelope hidden, or idempotency.

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?

Three sentences with zero fluff: purpose, UI prerequisite, and parameter units—all front-loaded and essential.

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?

Adequate for a 3-parameter tool without output schema; captures the domain-specific gotcha (envelope visibility) that would block successful invocation.

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?

Compensates for 0% schema coverage by providing essential units (seconds, dB) for position and value_db; track_index is self-explanatory but undocumented.

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 specific action (add volume automation point) and target resource (track), clearly distinguishing from set_track_volume (static) and add_pan_automation (different parameter).

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?

Provides critical precondition (envelope must be visible in REAPER UI) but does not explicitly contrast with static volume alternatives or state failure modes.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.