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

Beyond the annotations (idempotentHint, openWorldHint, destructiveHint=false), it discloses concrete behavior: previous codes are replaced, codes expire in 24 hours, resends are rate-limited to one per minute, and a same-op_key retry sends no extra email. That is meaningful operational context. It omits permission/authority requirements for the resend.

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 tight sentences, front-loaded with the core action and followed by operational constraints. Every clause carries information; the only wrinkle is the unexplained 'resend_after' reference.

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 single-parameter mutation with no output schema, the description covers replacement, expiry, rate limiting and idempotency, which is enough to invoke it correctly. It stops short of describing the response (e.g., whether a status/timestamp is returned) or the prerequisite that a change must be pending.

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% for the single op_key parameter, so the schema already documents format, length and retry semantics. The description's retry note largely restates the schema's op_key description, adding little new parameter meaning. 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 and resource ('Resend codes for the pending email change'), which separates it from siblings like cancel_email_change or confirm_notifications. It loses a point for referencing 'resend_after', a field that does not appear in the schema or annotations, leaving the trigger condition ambiguous.

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 the usage context (a pending email change whose prior code needs re-issuing) but never states explicitly when to call this versus cancel_email_change or another flow, nor what precondition makes resend valid. Usage is inferable, not spelled out.

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