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

Annotations already declare read-only, non-destructive, and non-open-world behavior, so the safety profile is covered. The description adds valuable behavioral context beyond annotations by explaining that monthlySends is the quota send_message draws from and that campaigns are metered separately under campaignSends. It does not cover authentication or response shape, keeping it from a 5.

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 three tight sentences with no filler. It front-loads what the summary contains, then adds a precise quota semantics note, then closes with usage timing. Every sentence 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?

For a zero-parameter read-only summary with no output schema, the description adequately describes what the agent will receive: mailbox/domain reachability, plan tier, and quota details. It could go slightly further in describing the return structure, but it is complete enough to call the tool correctly.

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?

The tool takes zero parameters, so there are no parameter semantics to document. A baseline of 4 is appropriate because the description does not need to compensate for any schema coverage gap.

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 gives a specific verb and resource ('Overview of the account') and enumerates exactly what the summary contains: reachable mailboxes/domains, plan tier, and monthly send quotas. It distinguishes the tool from send-oriented siblings by framing it as account-level information. It does not explicitly differentiate from get_setup_summary, which prevents a 5.

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 final sentence, 'Useful before large sends,' gives a clear context for when to call it. It does not name alternatives or state when not to use it, but it provides actionable timing guidance without being misleading.

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