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

Beyond the annotations, it discloses a real behavioral and cost trait: line breaks are billed and insert ~1.3s pauses, with an explicit instruction to strip them from formatted text. It also reveals the voice default and the return type (audio), adding substantial context without contradicting the annotations.

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 description is compact: two sentences for the core behavior and one focused warning paragraph. The main action is front-loaded, and every sentence earns its place.

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 tool with no output schema and a non-read-only annotation, the description supplies the essential return type (audio), the default voice behavior, and a critical billing caveat. The only notable gap is the language parameter, whose semantics are never stated.

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?

With 0% schema description coverage, the description must carry parameter meaning. It usefully clarifies voice (defaults to a Spanish voice; list_voices shows the catalogue) and warns about line breaks in text, but the language parameter is never explained. This is partial compensation for a fully undocumented schema.

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?

Opens with 'Read text aloud. Returns audio.' — a specific verb, resource, and output in one short sentence. This is unambiguously distinct from sibling audio tools like generate_music and transcribe_audio, even though no sibling names are called out.

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 clearly establishes the tool's role as text-to-speech and even routes the agent to list_voices for voice selection. However, it never states when to choose this over the other audio siblings or offers any exclusion criteria, so usage is implied rather than explicit.

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