Confirm Phone Verification

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

Annotations cover safety hints (readOnly=false, idempotent=true, openWorld=true), but the description goes well beyond them by disclosing post-success behavior (retry VERIFICATION_REQUIRED failures), the meaning of emailVerified: false, and the PHONE_CODE_INVALID failure semantics. This is exactly the contextual layer structured fields cannot carry.

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 purpose and prerequisite are front-loaded in the first clause, followed by success and error handling. It is a dense multi-clause paragraph but each clause carries actionable information; only slight tightening would help.

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 tool with no output schema, the description supplies the missing return semantics (emailVerified flag, PHONE_CODE_INVALID error) and the follow-up workflow. An agent has everything needed to call it and interpret the result.

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% with a single parameter whose format constraints (4-12 chars, case-insensitive) are fully documented in the schema. The description only restates that the code comes from the sibling tool, adding no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (verify) and resource (the account's phone number) plus the required input (the code), and explicitly ties the code's origin to the sibling tool send_phone_verification_code. An agent can distinguish it from send_phone_verification_code without opening either schema.

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?

Clearly states when to use it (after the user receives a code from send_phone_verification_code), what to do on success (retry the VERIFICATION_REQUIRED failure), and how to recover from failure (check code with user or send a new one). Both the success path and the error path route the agent to the correct next action.

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