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

With no annotations, the description carries the full burden and does well: it discloses the auth requirement, that ten one-time recovery codes are returned exactly once and must be stored, and that sign-in behavior changes going forward. It omits failure modes (e.g. calling when MFA is already on) and whether the operation is idempotent.

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?

Three short sentences, each carrying distinct information: precondition, action, return value, and downstream consequence. The trailing '(account.login code)' is slightly cryptic but does convey the future sign-in requirement without padding.

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 successfully covers the precondition, the one-time recovery-code return, and the resulting sign-in change. It could still cross-reference account_mfaRecoveryCodes or note behavior when MFA is already enabled, but nothing critical for correct invocation is missing.

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 0%, so the description must compensate, and it does: the single parameter is identified as a 6-digit code from the authenticator app, giving origin and format beyond the schema's bare minLength/maxLength bounds. It does not explain the 20-character upper bound, which suggests codes may include non-digit characters.

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: confirm an authenticator code to turn two-step sign-in on. The sequencing against account_mfaSetup is implied by 'confirm a 6-digit code', but no sibling tool is named explicitly, so differentiation is inferred rather than stated.

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?

Provides a real precondition ('Signed-in session only'), which tells the agent when the call is valid. However, it never states when not to use it (e.g. already enabled) or points to account_mfaSetup / account_mfaDisable / account_mfaRecoveryCodes as the alternatives for adjacent steps in the flow.

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