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

Adds context the annotations don't carry: the call spends credits, returns immediately (so results must be fetched later), and eleven-music silently ignores sample_rate, bitrate, and lyrics rather than erroring. Annotations already cover mutation/safety, so this is a solid supplement, though permissions and any credit amount/limit are not stated.

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-loads the purpose, the credit cost, and the async behavior in two short sentences before a compact model table. The only minor waste is repeating the model display names after the IDs, which is harmless.

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 presence of an output schema means return values need no explanation, and the cost/async facts are covered. But for a nine-parameter generation tool, the description omits how lyrics_optimizer and is_instrumental behave and how the prompt is interpreted, leaving meaningful ambiguity.

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 only 11%, so the description must compensate, and it does so for the model-specific parameter interactions (lyrics, lyrics_optimizer, sample_rate, bitrate). However, lyrics_optimizer, is_instrumental, audio_format, and the meaning of the prompt are left unexplained, so several of the nine parameters remain opaque.

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 and resource — start a music generation from a creative brief — which is unambiguous against siblings like generate_image, generate_voiceover, and generate_clip. The model list further narrows what the tool produces and under which engine.

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?

Gives selection guidance at the model level: eleven-music is instrumental only, takes no lyrics or lyrics_optimizer, and always emits MP3, which effectively tells the agent when to pick each model. It never names an alternative tool or a when-not-to-use condition, so it stops short of full routing guidance.

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