fx_get_pin_mappings

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

No annotations are provided, so the description carries the full burden. It clearly states it is 'Read-only' and 'without modifying anything', discloses the underlying API (TrackFX_GetPinMappings), and specifies the REAPER version requirement. It also documents the return format (pin, track_channels, raw bitmasks) and mentions 'lossless round-trips', covering behavioral expectations beyond the bare action.

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 efficiently structured: a one-line summary, a concrete use case, a bulleted return format, a version note, and an Args block. Every section adds value, and the purpose is front-loaded. It is detailed without being verbose.

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 read-only inspection tool with no output schema, the description is complete: it explains parameters, return values, version requirements, and the non-destructive nature. It covers all information an agent needs to invoke it correctly and interpret the result, leaving no critical gaps.

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?

The input schema has 0% description coverage, but the description includes an Args section that explains each parameter fully: track_index is 0-based or -1 for master, and fx_index is 0-based. This adds significant meaning beyond the schema's bare integer types, fully compensating for the lack of schema descriptions.

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 uses a specific verb ('inspection') and resource ('audio input and output pin mappings') and clearly differentiates this tool from generic FX tools like fx_get_chain by focusing on pin-level wiring. It states exactly what it returns and includes a concrete use case (verifying sidechain routing), so an agent can easily understand its purpose.

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?

The description explicitly says 'Use this to verify existing sidechain routing without modifying anything' and gives an example (Pro-Q 4 sidechain pins receiving channels 3/4). This provides a clear when-to-use scenario and implies it should not be used for modifications, which is reinforced by the 'Read-only' phrase. It effectively distinguishes it from mutation tools among siblings.

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