submit_verification_code

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

Annotations only declare readOnlyHint=false and destructiveHint=false. The description adds substantial context beyond that: the out-of-band delivery precondition, the exact 400 unsupported_for_type failure mode, and the account/credential prerequisite (Proof account, PROOF_API_KEY, restart, and that start_login does not unlock it).

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?

Front-loads the core action, then the acceptance constraint and the alternative routing, then the access prerequisite. Despite being detailed, every sentence carries distinct, decision-relevant information and none is wasted.

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 two-param mutation tool with no output schema, it covers the safety profile (via annotations plus stated error behavior), the precondition for success, the failure path, alternative tools, and the authentication requirement. Nothing an agent needs to invoke it 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 description coverage is 100% for both id and code, so the schema already carries parameter meaning. The description clarifies that the code is an OTP/challenge submitted for a pending verification but adds no format or value details beyond the schema. Baseline 3 is appropriate.

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 (submit) and resource (OTP/challenge code) scoped to a pending verification. It further narrows the accepted type/channel combinations, so an agent can distinguish it from trigger_verification and the other verification siblings without opening 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?

Explicitly names when the tool applies (type email; type domain with channel email) and when it does not (any other pair returns 400 unsupported_for_type). It routes the agent to trigger_verification for domain over dns/http/auto and explains how phone, social, and telegram_bot complete instead.

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