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

Annotations already declare non-read-only, non-destructive, closed-world. The description adds two things annotations cannot: an authentication prerequisite (customer's Happy Hamper login) and a return-value behavior (serviceZoneId is null when the address is out of the pickup area). It doesn't say what happens on duplicate addresses or whether saving 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, action first, then the out-of-zone caveat, then the auth note. No filler; each sentence carries distinct information.

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 usefully covers the one return signal an agent needs to interpret (null serviceZoneId). Auth requirement is stated. It stops short of describing what a successful save returns (an address id?) or validation failure modes.

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 86%, so line1, line2, city, state, postalCode, label and note are all already documented in the schema. The description adds nothing parameter-specific, so the 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?

Specific verb + resource: 'Save a pickup or dropoff address' makes the creation of a delivery address unambiguous. It doesn't distinguish itself from the sibling update_address or check_address, which is the only gap.

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?

No statement of when to use this versus update_address (change an existing one) or check_address (validate serviceability), even though both siblings compete directly. Usage must be inferred from the verb 'save' alone.

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