createSession

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

Description adds significant behavioral context beyond annotations: it explains no audio starts on creation, details the single-use/expiring ws_url, and clarifies server-side responsibility. Annotations indicate mutation but not destructive, which aligns. No contradiction.

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?

Well-structured with two focused paragraphs and a tag. First paragraph defines purpose and context; second gives usage instructions. The tag 'Tags: Sessions' is minor extra. Could be slightly tighter, but effective and front-loaded.

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?

No output schema, but description explains the return value (ws_url) and its properties (single-use, expires). Covers the two-step flow and security constraints. Minor lack of error handling details, but adequate for a simple session creation tool.

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 baseline is 3. The description does not elaborate on parameter details beyond the schema; it mentions agent_id indirectly but adds no new semantic information. The custom_variables description in schema already covers tampering risk, so description adds marginal value.

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 'Create a voice Session: a short-lived, single-conversation reservation that lets a client hold a live voice chat with your agent.' It uses specific verbs and resources, and the sibling tools list shows no overlap with voice sessions, so it distinguishes well.

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?

Explicit step context: 'This is step 1 of 2.' Provides clear when-to-use guidance ('Call this endpoint from your server... return only the ws_url to your client'), and strong exclusions ('The API key must never reach the browser'). It also references alternative resource for the next step.

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