send_sms_verification_code

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

Annotations already indicate the tool is not read-only (readOnlyHint false), not destructive (destructiveHint false), and idempotent (idempotentHint true). The description adds the specific behavior of sending a 6-digit code via Twilio but does not elaborate on rate limits, response behavior, or any side effects beyond the core action.

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 two sentences, front-loaded with the essential purpose, and every sentence adds value. No extraneous 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?

Given the simplicity of the tool (3 parameters, no output schema), the description covers the core action and use cases. However, it lacks details on return values, prerequisites (e.g., user must have a phone number on file), and potential errors. Annotations exist but do not fully compensate.

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 low (33%: only phone has a description). The description does not add any parameter meanings beyond the schema; it fails to explain the 'context' or 'purpose' parameters or their valid values. This is a significant gap given the low schema coverage.

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 ('send a 6-digit verification code'), the channel ('via SMS (Twilio)'), and the use cases ('purchase confirmation or high-value action verification'). It distinguishes from sibling tools like 'send_email_verification_code' (different channel) and 'verify_code' (different operation).

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 provides explicit use cases ('purchase confirmation or high-value action verification'), giving context for when to use. However, it does not mention when not to use or explicitly list alternatives like email verification, though context can be inferred from sibling tools.

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