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

With no annotations, the description carries the full burden. It usefully discloses that the call costs 1 credit and returns base64 MP3 audio. However, it does not address authentication via api_key, input length limits, or possible error behavior, leaving important behavioral gaps.

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 two short sentences: the first front-loads the action and cost, the second gives the return format. Every phrase earns its place with no redundancy.

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 simple 3-parameter tool, this is minimally viable: the required text parameter is obvious, the output format is stated, and the cost is disclosed. However, the lack of usage guidance, voice/api_key semantics, and any reference to echo_voices for voice discovery leaves clear gaps.

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 0%, and the description only clarifies the text parameter ('from text'). It does not explain voice choices, the role of api_key, or how the defaults behave, leaving two of three parameters underspecified.

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 action and resource: 'Synthesize speech from text' and specifies the output as base64 MP3 audio. This is clear, but it does not explicitly distinguish the tool from siblings like echo_voices or echo_order, so it falls short of a full 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?

There is no guidance on when to use this tool versus siblings, nor any exclusions or prerequisites. The '1 credit' note hints at a cost trade-off, but it does not provide actionable selection guidance.

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