ACTION_TEXT_TO_SPEECH

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

With no annotations at all, the description carries the full burden and does disclose real behavioral traits: blocking until speech finishes, an environment prerequisite, and the two result variables (tts_success, tts_error). It omits error-handling/timeout semantics that appear only in the schema, keeping it from a 5.

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?

A single compact sentence that front-loads the core action, then the blocking behavior, then prerequisites and outputs. Every clause carries information; only mild density from cramming output keys and interpolation into one line.

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 an 8-parameter side-effecting tool with no output schema, it covers the essential context: what happens, that it blocks, that an external engine is required, and what result keys come back. Missing detail on failure/timeout behavior is partly recoverable from the schema's on_error and timeout_ms entries.

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 the schema already documents every parameter including ${var} support and enum values, which sets a baseline of 3. The description only restates the ${var} interpolation rule at a generic level and adds the return-variable names, so it adds little beyond the 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?

The description states a specific verb and resource ('用系统 TTS 朗读文本') and adds the distinctive blocking semantic ('读完才继续'), which no sibling such as ACTION_TOAST or ACTION_MEDIA_CONTROL shares. It stops short of naming any sibling for differentiation, so a 4 rather than a 5.

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?

It gives a prerequisite ('需系统已装 TTS 引擎') and the implied usage of synchronous narration in a workflow, but there is no explicit when-not guidance and no pointer to alternative tools for audio output, leaving selection to inference.

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