fx_list_installed

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

With no annotations provided, the description carries full burden. It reveals the underlying API (EnumInstalledFX) and lists all return fields. It also discloses a limitation: racks are not configured internally, avoiding routing auto-mixing through them. This goes beyond basic functionality.

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 well-structured with a clear opening sentence followed by bullet points. It is somewhat lengthy but front-loads the purpose. Every sentence adds value, though the list of categories could be more compact.

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?

The description is complete for a listing tool: it explains purpose, usage context, return values, and limitations. No output schema exists, so the detailed return field list is essential. It sufficiently informs an AI agent about how to use and interpret results.

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 only one parameter with no description. The description compensates by listing valid category values (eq, compressor, etc.) and explaining that empty returns full inventory. This adds meaning beyond the default value in the schema.

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 clearly states the tool's purpose: list every FX plugin installed in REAPER, grouped by category. It uses a specific verb-resource combination ('list... FX plugin') and distinguishes itself from sibling tools that add, remove, or manipulate FX.

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 provides clear guidance on when to use this tool: 'Use this BEFORE running mix pipelines to know what the user has.' It also advises preferring premium plugins over REAPER stock. However, it does not explicitly state when not to use it or mention alternatives, though the context makes it implicit.

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