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

The description adds a useful behavioral detail beyond the annotations: setting is_default_shipping=true makes the new address the default. However, it does not disclose whether creating a new default unsets an existing default, whether duplicate addresses are allowed, or any permission-related behavior. With annotations only indicating readOnlyHint=false, this is partial but not comprehensive disclosure.

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 description is two short sentences with no filler. The primary action is front-loaded, and the only extra instruction concerns the most stateful parameter. Every word earns its place.

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?

Given the schema's thorough parameter documentation and simple create operation, the description is nearly complete. It adequately states the action and the key behavioral flag. The main omissions are return-value behavior and side effects on an existing default address, but these are not critical for a straightforward creation tool with no output schema.

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 the baseline applies. The description repeats the is_default_shipping behavior already documented in the schema ('When true, make this the buyer's default shipping address') without adding new parameter meaning. The schema itself carries the parameter semantics.

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?

The description opens with a specific verb and resource: 'Save a new shipping address.' This clearly identifies a create operation for a shipping address and distinguishes it from the sibling tool addresses_list, while also signaling it is not an update or list operation.

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 usage by being the only address-creation tool and gives a direct hint about setting is_default_shipping, but it does not explicitly state when to use this tool versus alternatives or mention any exclusions. There is no competing address-create sibling, so the context is reasonably clear but not fully explicit.

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