settings

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

Annotations already declare readOnlyHint=true, and the description reinforces it with 'Changes nothing.' More valuably, it discloses a permission boundary beyond the annotations: mailboxes, modes, sending limits and the passphrase are user-only and must be changed on the settings page. It does not discuss pagination or response shape, but the output schema covers returns.

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 purpose well, but the middle clause is a long comma-separated inventory of returned fields that duplicates what the output schema already conveys, so part of the text does not fully earn its place. The closing permission note is efficient and useful.

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 an output schema exists and annotations cover the read-only safety profile, the key remaining gap an agent faces is whether it may modify anything; the description answers that clearly. Only the positive invocation trigger is left implicit.

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?

Zero input parameters, so there is nothing to disambiguate; the baseline of 4 applies. The description adds no parameter info, which is appropriate here.

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 clear verb+resource ('Show the settings') and enumerates the specific settings surfaced, making it distinguishable from accounts, folders, and other read siblings. It also names change_setting as the mutation counterpart, though the boundary is stated in passing rather than crisply.

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?

Explicitly routes changes to change_setting and adds the condition 'only when the user asks', which is real when-to-use guidance. It does not spell out the positive trigger for calling this tool (e.g., 'when the user asks what settings exist or what you can configure'), leaving that to inference.

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