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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses that codes expire after 15 minutes, but says nothing about what a successful confirmation changes, retry/rate-limit behavior, or failure modes—gaps that matter for an un-annotated mutation-style tool.

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?

Two short sentences with zero waste. The core action is front-loaded and the expiry constraint follows immediately, so nothing needs to be skimmed for.

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?

With no output schema and no annotations, the description is the only source of behavioral context, and it covers only the input source and expiry. It omits the result of a successful verification and error handling, which leaves the definition adequate but incomplete for a tool whose structured metadata is thin.

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%: the schema already documents the 6-digit pattern for 'code' and the origin of 'agent_key' from agent_register. The description's mention of the 6-digit code adds nothing 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 ('Confirm') and resource ('the 6-digit code sent by agent_contact_set'), which also distinguishes it from agent_contact_set (the sender) and agent_endpoint_verify (the endpoint counterpart). It does not explicitly say the outcome is marking the owner email verified, so it falls just short of a 5.

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?

Implies the prerequisite workflow (the code must come from agent_contact_set) and adds a time constraint ('Codes expire after 15 minutes'), which is useful usage guidance. However, there is no explicit statement of when to call it versus alternatives or what to do if the code is expired or wrong.

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