submit_verification_code

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

With no annotations provided, the description carries the full behavioral burden. It discloses the 400 unsupported_for_type error, the out-of-band delivery requirement, the PROOF_API_KEY access prerequisite, and restart guidance. It does not describe what a successful submission returns or whether the verification is completed synchronously, but it is unusually transparent for a tool with no annotation support.

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 dense but every sentence earns its place: purpose, acceptance constraints, alternatives, and access requirements. The most important routing information is front-loaded, and the access note is cleanly separated at the end.

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 2-parameter tool with no output schema and no annotations, this description is remarkably complete. It tells the agent exactly which verification types/channels are valid, what happens for invalid pairs, which sibling to use instead, and what setup is required. Nothing essential to invoking the tool correctly is missing.

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 schema already documents id and code. The description adds contextual value by clarifying that the code must have been delivered out-of-band and that the id refers to a pending verification, but it does not significantly expand on the parameters' format or constraints beyond what the schema provides.

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 opens with a specific verb and resource: 'Submit an OTP/challenge code for a pending verification.' It then sharply scopes the accepted cases ('type email' and 'type domain with channel email'), which distinguishes it from siblings like trigger_verification and verify_email_otp without needing to inspect schemas.

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 explicitly states when this tool is accepted and when it is not. It names trigger_verification as the alternative for domain-over-dns/http/auto, explains how phone, social, and telegram_bot verifications complete elsewhere, and even warns that start_login does not open this tool. This leaves little ambiguity about selection.

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