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

Beyond the annotations (which already signal a non-read-only, idempotent, open-world write), the description discloses three non-obvious behaviors: the response is identical whether or not handle and address match (anti-enumeration), op_key scoping semantics where a different address under the same key is a new request rather than a conflict, and a rate limit of at most three outstanding codes per identity.

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 action is front-loaded in the first clause, and every subsequent clause carries real information. The parenthetical covering op_key semantics is dense and slightly convoluted, but it is not wasted space.

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 request-style operation with no output schema, the description supplies the missing pieces an agent needs: idempotency behavior, anti-enumeration response handling, and outstanding-code limits. Nothing essential is absent.

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 baseline is 3, but the description adds genuine meaning beyond the schema for op_key, clarifying that it is remembered per handle+address and that a different address under the same key is a separate request rather than a conflict. Handle/email relationship semantics are also illuminated.

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 names a specific verb and resource ('Send a recovery code to the identity's verified email') and identifies the trigger target precisely. It does not, however, distinguish this from the sibling recover_credential, leaving the agent to infer which recovery path applies.

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 implies when the tool is relevant (requesting a recovery code for an identity) but never states when to prefer it over siblings like recover_credential or resend_email_verification, nor any preconditions aside from the verified-email matching. Usage is implied, not directed.

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