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

Beyond the annotations (which only mark it as non-read-only, non-destructive, open-world), the description discloses the concrete side effects: files written to the project path and their naming (out_1.wav, out_2.wav, ... or out), plus the returned task_id and credit cost. It doesn't quantify credit cost or describe failure/retry behavior, so it is strong but not exhaustive.

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?

Three dense sentences that front-load the core action and the voice source, then the output-file convention, then the return values. No filler and nothing redundant with the schema.

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 correctly covers return values (task_id, credit cost) and file side effects, and it flags the dead describe parameter. It leaves the multi-line/out interaction lightly sketched and says nothing about task polling, which an agent would need to resolve via composer_task_status.

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%, so the baseline is 3, but the description adds real meaning: the mutual exclusivity of voice_id and like, that voice_id is a provider id rather than a record UUID, and that the out path is mutated per line when multiple lines are supplied. That clarifies fields whose schema text alone leaves the interaction between them ambiguous.

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 ("Speaks one or more lines") with the exact voice sources it accepts, which makes TTS distinct from siblings like composer_generate_music or composer_generate_clip. It does not explicitly name or contrast those siblings, so routing still requires the agent to infer from names.

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 clear operating constraints: "use exactly one provider voice_id or authorized like samples", "No voice design", and that describe is rejected before charging. It routes to composer_list_voices for voice_id. It stops short of an explicit when-to-use-this-vs-alternative statement for the surrounding generation tools.

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