VOICEVOX TTS MCP

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: text is split by line breaks into separate speech units, each line processed independently, and the first line should be short for quick playback start. It doesn't mention error handling, rate limits, or authentication needs, but covers core playback behavior adequately.

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 front-loaded with the core purpose in the first sentence, followed by specific behavioral details in the second. Both sentences earn their place by providing essential information without redundancy. It's appropriately sized for the tool's complexity.

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?

Given no annotations and no output schema, the description does well to cover the main behavior and text processing logic. However, it doesn't address potential side effects (e.g., interrupting current playback, which is hinted at in the 'immediate' parameter schema), error cases, or what the tool returns. For a 7-parameter tool with mutation implications, it's good but not fully complete.

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 all 7 parameters thoroughly. The description adds minimal parameter semantics beyond the schema—it mentions line break processing and first line optimization, which relates to the 'text' parameter but doesn't significantly enhance understanding of parameters like 'query' or 'speaker'. Baseline 3 is appropriate given high schema coverage.

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 clearly states the specific action ('Convert text to speech and play it') and resource (audio output), distinguishing it from siblings like 'synthesize_file' (file output) and 'stop_speaker' (playback control). It explicitly mentions text processing by line breaks, which adds specificity beyond the basic function.

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 implies usage for text-to-speech playback but doesn't explicitly state when to use this tool versus alternatives like 'synthesize_file' (for file output) or 'generate_query' (possibly for query generation). It provides some context about line break processing but lacks explicit guidance on tool selection scenarios.

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