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

Annotations already cover read-only and open-world behavior, and the description adds important context beyond them: credential validity (1-12 hours), pricing ($0.10 per hour, $1.2 USDC per call via x402), and the global NAT/firewall traversal purpose. It does not detail credential expiry or output structure, but the added cost and payment model are valuable behavioral context.

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?

Three short sentences with no filler. The core purpose is front-loaded, followed by pricing and validity constraints efficiently.

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 one-parameter credential-issuing tool with no output schema and useful annotations, the description covers what is returned ('credentials', 'ICE servers') and the cost model. It is nearly complete, though it could say more about credential format or expiry handling.

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%, so the hours parameter is already documented as '1-12, default 1'. The description adds meaning by tying the hours value to pricing ('$0.10 per hour of validity'), which helps an agent reason about the parameter's cost impact.

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 names a specific resource (TURN relay credentials / ICE servers for WebRTC audio and video) and explains the concrete problem it solves (connecting through corporate and home firewalls and NATs). This clearly distinguishes it from sibling voice/turn tools.

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 implies the usage context ('for voice and video agents') but does not explicitly say when to choose this tool over alternatives or when not to use it. No prerequisites or exclusions are stated, leaving the agent to infer the use case.

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