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

Annotations already mark this as a non-readOnly, destructive, non-idempotent, open-world write, and the description is fully consistent with that while adding real context: the link is valid 7 days, a password is never placed in a message, the send happens once per customer, and resend invalidates the previous link. It also discloses the hard refusal on missing phone number for SMS, which no annotation conveys.

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 staff-only restriction and the mandatory channel question are front-loaded, and every sentence carries operational weight (validity window, no-password rule, once-per-customer, resend semantics). It is a dense paragraph rather than broken into scannable lines, which costs a little readability.

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, the description still covers the essential outcome (a link is sent, valid 7 days) and the preconditions (channel choice, phone for SMS). What happens on failure or what identifier the caller gets back is not stated, but for a fire-and-notify tool this is close to complete.

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 description coverage is 100%, so email, resend, notifyVia and phoneNumber are already documented in the schema, including the SMS-conditional requirement. The description reinforces the 'no default, ask the user' rule for notifyVia and the refusal behavior, but adds little syntax or format detail beyond the schema, so the baseline 3 is appropriate.

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+resource (send a customer welcome) and elaborates what that means concretely: telling the customer their account exists and giving them a password-setup link. An agent can distinguish this from nearby siblings like create_customer_account or send_password_reset without opening any schema.

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?

Gives clear operating conditions: STAFF ONLY, always ask the channel because there is no default, and only pass resend when someone explicitly asked. It does not, however, name or contrast against sibling tools (e.g. send_password_reset) that an agent might otherwise pick, so the routing guidance is context-rich but not alternative-aware.

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