Email preferences

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

readOnlyHint=true already tells the agent this is a safe read, and the parameterless schema confirms nothing is mutated. The description does add real behavioral value by naming the returned fields and explaining what `ready` means, but it stops short of saying whether preferences are per-instance or per-user, or what an empty result implies.

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 tight sentences with the core answer front-loaded and the return shape immediately after. No filler, though the field walkthrough is slightly terse and could be grouped more cleanly.

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?

With no output schema, the description carries the burden of explaining the return value and does so, covering both emailEnabled and the ready note. For a trivial parameterless read tool that is close to sufficient; only the relationship to the setter tool 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 parameters, so the baseline is 4. The description uses its space on output field semantics instead, which the schema cannot cover, so nothing is lost by the absence of parameter discussion.

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 identifies the resource concretely: which optional emails the instance sends, broken down by topic, with the top-level return shape given. The verb is implied (a read/query) rather than stated outright, and the sibling set_email_preferences is never named, so the agent must infer the read-vs-write split itself.

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?

There is no statement of when to call this versus set_email_preferences or get_instance_settings. The note that emailEnabled false means no mail is sent is interpretive context, not a usage condition, so an agent gets no routing guidance.

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