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

Goes well beyond the annotations: it discloses the anti-enumeration uniform response, that op_key is scoped to the handle+address pair (so a different address under the same key is a new request, not a conflict), and the outstanding-code cap of three per identity. These are exactly the operational details an agent cannot get from readOnlyHint/idempotentHint/openWorldHint.

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-loaded with the action in the first sentence, then the operational caveats. Dense but every clause carries information; the nested parenthetical is heavy but not 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?

No output schema exists, and the description compensates by telling the caller the response is deliberately indistinguishable regardless of match outcome. The only gap is that it does not say what a successful response actually contains (an acknowledgement vs. a token), which matters for the downstream recover_credential step.

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 still adds meaning: the handle and address must match for a code to be delivered yet the response is identical either way, and the op_key's scoping to the handle+address pair is spelled out beyond the schema's retry wording.

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 concrete verb and resource: send a recovery code to the identity's verified email. An agent can tell this is the initiation step of account recovery, but the description never names its obvious sibling recover_credential, so the request/confirm split is left implicit.

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: it says what inputs it takes and what happens on a handle/email mismatch, but never says 'call this first, then use recover_credential' or when not to call it. An agent must infer the workflow ordering from the sibling list.

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