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

Goes well beyond the annotations: it explains the real-world consequence ('Drivers see these on every pickup and delivery there'), which justifies destructiveHint=true, and clarifies the destructive mechanic (empty string clears a field) and the idempotent overwrite semantics of saving. It also discloses the auth prerequisite (connected account). This is exactly the extra context annotations cannot carry.

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-loads the prerequisite and core action, then packs field meanings, visibility consequence, default behavior, and the clear-field convention into compact clauses with zero filler. Every sentence carries information an agent needs to call the tool correctly.

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 an all-optional mutation tool with no output schema and annotations covering safety, the description supplies the missing pieces: auth requirement, what gets persisted, who consumes it, default-address handling, and how to clear values. Nothing needed for a correct invocation is absent.

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?

Adds meaning the schema lacks: gateCode is a gate/building/lockbox code, howToGetIn covers buzzer/doorman/side entrance, and addressId defaults when omitted. whereToLeaveBag is left to its name and max-length schema entry, and the 40/200/500 char limits remain schema-only, so it falls just short of full coverage of a 75%-documented schema.

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: it saves how a driver gets in at one of the customer's saved addresses, and enumerates the exact fields being written (gateCode, howToGetIn, whereToLeaveBag). No sibling tool covers this resource, so an agent can distinguish it immediately from update_care_preferences or update_recurring_pickup.

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 explicit operational guidance: 'Omit addressId for the default address' and 'Pass an empty string to clear a field', plus the prerequisite that a connected Fold account is required. It stops short of stating when NOT to use it or naming an alternative tool, so it is clear context without explicit exclusions.

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