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

Annotations only declare readOnlyHint=false and destructiveHint=false, so the description carries real weight here and does so well: it discloses that previously issued codes and links stop working and gives concrete rate limits of 3 per hour and 6 per day. It stops short of saying what happens when the quota is hit or what channel delivery uses.

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, front-loaded with the action and immediately followed by the consequence and the limits. Every clause adds information an agent would otherwise lack; nothing is repeated from annotations or schema.

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?

An output schema exists, so return values need no explanation, and the invalidation and throttling behavior are covered. The remaining gap is rate-limit failure behavior and any precondition such as an existing owner record, which matters for a state-changing tool with no parameters to signal intent.

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?

The tool takes no input parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The parenthetical about old codes expiring is the only semantic caveat an agent needs before calling with an empty object.

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 and resource: sends a fresh code and link to the owner, with the qualifier that prior codes and links are invalidated. An agent can distinguish this from general reads in the sibling set, though it never contrasts itself with verify_owner, which is the closest ambiguous neighbor.

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?

Usage is implied rather than stated: you call this when the owner needs a new code or link, and the invalidation note signals it should not be used casually. There is no explicit when-not guidance and no reference to the sibling verify_owner, so the agent must infer the boundary.

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