Update mail forwarding settings

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

Annotations already provide idempotentHint and openWorldHint. The description adds valuable details like the clearing behavior for empty arrays and normalization of Japanese domains. It also notes that keep_in_mailbox is unchanged if omitted. This adds context beyond annotations.

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 a single sentence with an additional clarifying sentence. It is concise and front-loaded with the main action. However, it could be more structured with explicit usage notes.

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?

The description covers the main operation and parameter effects but lacks information about return values, prerequisites (e.g., domain verification), or side effects. For a mutation tool with no output schema, this is adequate but not 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 coverage is 100%, so baseline is 3. The description slightly adds by repeating the clearing behavior, but this is already in the schema. No new parameter meaning is provided beyond what the schema already conveys.

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 clearly states the verb (overwrite update) and resource (mail forwarding settings for a specified account), distinguishing it from sibling tools like get_mail_forwarding. It also specifies that passing an empty array clears all forwarding addresses.

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 it is for updating forwarding settings but does not explicitly state when to use it or when not to. No alternatives or exclusions are mentioned, leaving the agent without guidance on selecting this tool over siblings.

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