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

Annotations only declare readOnlyHint and openWorldHint; the description adds substantial context beyond them: streaming protocol details, the StartOfTurn/EndOfTurn signals, session length bounds, and the x402 payment model with exact costs. It stops short of documenting auth mechanics or session termination behavior, so it is not 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?

Two sentences, zero filler. Core capability and event model come first, and the cost/payment facts are appended as a compact second sentence. Every clause carries operational information.

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 streaming session tool with no output schema, the description covers protocol, emitted events, duration bounds, and cost. It leaves open how the session is authenticated/terminated and the lifetime of the returned URL, which an agent might need.

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 four parameters. The description reinforces the length bound (1-60 minutes), the PCM/sample-rate relationship, and the turn-detection semantics behind eot_threshold, but adds no syntax or defaults 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?

States a specific verb chain and resource: obtain a WebSocket URL, stream raw 16-bit PCM, receive live transcripts and turn events. This is clearly distinct from batch siblings like transcribe, though the description never names those alternatives explicitly.

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 phrase 'for voice agents' and the emphasis on live streaming and end-of-turn detection imply when to use it, but there is no explicit when-not-to-use guidance and no routing to transcribe/voice_turn for non-realtime cases. Usage is inferable rather than stated.

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