add_bus_to_mix

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

Annotations cover the basic safety profile (readOnly false, destructive false, non-idempotent), but the description adds real behavioral detail beyond them: that the mix is saved (a disk side effect), that duplicates are silently skipped (already_in_mix true, not saved), and the returned status fields. This goes meaningfully beyond the hints.

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?

Front-loaded with the core action and side effect, then the dedup rule and alternative. Efficient overall, though the trailing 'Returns:' line largely repeats fields already named in the preceding sentence, adding slight redundancy.

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, the description appropriately enumerates the returned fields and explains the already_in_mix/add/save behavior an agent needs to interpret results. It is essentially complete for this low-complexity mutation, missing only explicit notes on failure modes.

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 description coverage is 100%, so both bus_path/mix_path and default_value are already documented. The description restates default_value as the new stage's target value but adds no format, range, or unit information beyond the schema. Baseline 3 applies.

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 a specific verb (Adds), the exact resource types (USoundControlBus to USoundControlBusMix) and the resulting action (as a new stage, saves the mix). It is clearly distinguishable from sibling tools like set_control_bus_mix_stage_value and remove_bus_from_mix.

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 states the key condition ('a bus already in the mix is left unchanged') and routes editing of an existing stage to set_control_bus_mix_stage_value. It gives clear usage context but does not name remove_bus_from_mix as the inverse operation.

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