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

Annotations indicate a write operation (readOnlyHint false) and not destructive. The description adds the behavioral requirement of explicit user confirmation and the need to present details before creation. This goes beyond annotations and is consistent with them; no contradiction found.

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 concise (two sentences) and front-loads the primary action and the critical confirmation step. It avoids redundancy, though given the tool's complexity, it could benefit from slightly more structure or bullets, but it is appropriately sized for a short description.

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?

This is a complex creation tool with 13 parameters, nested objects, and an output schema. The description is too sparse: it does not mention what the tool returns, any side effects, prerequisites (e.g., phone number existence), idempotency behavior (though idempotencyKey has a schema description), or relationships to other tools. Given the complexity, the description is incomplete for an agent to call it correctly without additional investigation.

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 only 15% (2 of 13 parameters have descriptions). The description only mentions name, voice, model, and transcriber, providing minimal guidance. It does not compensate for the low coverage by explaining the purpose or constraints of the other nine parameters (e.g., isDefault, description, firstMessage, systemPrompt, flags). The only helpful hint is about omitting transcriber.

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 the action ('Create an outbound assistant') and the resource, and distinguishes it from update/delete/list by the action verb. It also adds a critical workflow requirement (explicit confirmation). However, it does not explicitly differentiate from creating an inbound assistant, though the name makes that clear.

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 description gives some usage guidance: it mandates showing the user the name, voice, and model for approval, and mentions that omitting transcriber accepts the platform standard. It does not, however, state when to use this tool versus update_outbound_assistant or other alternatives, nor any exclusions.

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