metasound_add_interface

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

Annotations already establish this is a non-read-only, non-destructive, non-idempotent editor mutation. Beyond that, the description discloses real behavioral context the annotations cannot: the edit is performed on the saved asset via FindOrBeginBuilding (the 'reliable headless path'), the interface is validated before mutation, and the asset is saved after the edit. It does not explain what happens when validation fails or what a second add does, despite idempotentHint=false.

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 purpose is front-loaded in the first sentence, and the return shape is cleanly stated. The middle sentence leans into internal implementation names (FindOrBeginBuilding, UMetaSoundBuilderBase::AddInterface) that a caller cannot act on, which is slightly more than needed, but the overall length is proportionate.

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?

With no output schema present, the inline Returns object (asset_path, node_kind, interface_name, added, saved) is genuinely load-bearing and fills a real gap. Mutation semantics, validation, and persistence are all covered; only failure behavior and repeat-invocation semantics are left unaddressed.

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 100% with two fully described parameters, so the baseline is 3. The description adds no format or path-syntax guidance beyond the schema (it only echoes asset_path and interface_name in the return list), so it neither compensates nor detracts.

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 gives a specific verb and resource: 'Adds a registered interface to an existing MetaSound Source's graph,' which is a distinct asset-level operation. It is clear on its own, but it does not name or contrast itself with the nearby sibling tools (add_metasound_graph_input, add_metasound_graph_output, metasound_add_node_by_classname), leaving the boundary to the reader's knowledge of MetaSound internals.

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?

Usage is only implied: the word 'registered' and the mention of IsInterfaceRegistered validation hint that the interface must already exist before calling, and that the target must be a saved MetaSound Source asset. There is no explicit when-to-use/when-not guidance and no named alternative (e.g., add_metasound_graph_input for plain graph inputs).

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