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

Goes well beyond the annotations by disclosing the output format (WAV, base64-embedded), the 2500-character input cap, the exact cost (0.025 USDC), the payTo address, and the 402-challenge retry mechanism with the forwarding headers. Annotations cover safety only, so this added operational context is exactly the value the description should provide.

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?

Front-loads the identity and output format, then the hard limits, then payment mechanics in three compact sentences with no filler. The payment sentence is dense but every clause is actionable; slight information crowding is the only knock.

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 two-parameter tool with no output schema, the description supplies return format, size limit, cost, and payment/auth flow — nearly everything needed to call it successfully. Minor omissions remain, such as error behavior when payment forwarding fails, keeping it short of a 5.

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% and both parameters carry their own descriptions, including the default voice (en_US-lessac-medium). The description only restates the 2500-character limit already enforced by maxLength, adding no syntax, format, or voice-selection guidance beyond the schema — baseline 3.

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 (self-hosted Piper text-to-speech) and what it produces (WAV audio returned as base64 in the tool result). Siblings are unrelated (brand_feedback, summarize, sol_*), so no ambiguity arises, and an agent can tell immediately what this tool does.

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 explicit invocation procedure: pay the resource URL in the 402 challenge, then retry with PAYMENT-SIGNATURE or X-PAYMENT, and notes the 0.025 USDC cost. It does not compare against alternatives or state when-not-to-use, but the prerequisite/payment flow is spelled out clearly enough to act on.

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