fx_rename

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the operation is cosmetic, that the plugin is unchanged, mentions the mix engine's internal use, and discloses the REAPER version requirement with a clean error on older versions. This is solid transparency for a rename operation, though it could say more about failure modes for invalid indexes.

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?

Every sentence adds value: purpose, usage, parameter docs, and version compatibility. The description is front-loaded with the core action in the first sentence, then provides context and technical details without fluff. It is appropriately sized for a 3-parameter tool.

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 rename tool with no output schema and no annotations, the description covers purpose, usage context, all parameters, and version requirements. An agent has enough information to call it correctly and know what to expect. No critical information 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 coverage is 0%, so the description must fully document the parameters, and it does. It explains track_index as 0-based with -1 for master, fx_index as the slot within the chain, and new_name with a max length of 1000 characters. This adds substantial meaning beyond the bare schema titles.

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 a specific verb and resource: 'Rename an FX instance's display label', and immediately clarifies the cosmetic nature ('plugin unchanged'). This clearly distinguishes it from siblings like fx_move or track_rename, so an agent knows exactly what this tool does without opening the schema.

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 gives a clear use case: tagging FX you've added yourself so later cleanup can find them, and notes the mix engine's internal prefix convention. It does not explicitly name alternative tools or state when not to use it, but the context is specific enough for an agent to decide. This matches 'clear context, no exclusions'.

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