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

With no annotations, the description carries the full burden and does so well: it enumerates every return status (approved, wrong_code, expired, too_many_attempts, already_used, replaced, not_found), discloses the 5-wrong-code lockout, states codes are single-use ("works once"), and notes it consumes no allowance.

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?

It is information-dense but front-loaded: purpose first, then parameter routing, then return semantics. Slightly run-on, but every sentence adds actionable content and nothing is redundant.

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 3-param tool with no output schema and no annotations, the description covers returns, edge-case statuses, lockout policy, and billing impact, which is nearly everything an agent needs. It stops short of noting any auth requirement, but the operational picture is essentially complete.

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 baseline is 3, but the description adds meaning: "to" resolves to the newest code sent to that address, while "id" is the identifier from verify_start. This clarifies the to/id/code interplay beyond the terse schema strings.

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+resource ("Check a code from verify_start") and explicitly anchors to the sibling verify_start, so an agent can place it in the two-step verify flow without opening the schema. It is clearly the check step as opposed to the start step.

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 opening clause ties the tool to the verify_start output, giving clear usage context, and "Uses no allowance" signals a billing distinction versus other tools. It does not state explicit exclusions or alternatives, but for a single-purpose step tool the context is clear.

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