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

Annotations already cover read-only and closed-world safety. The description goes further with two high-value semantics the agent cannot get elsewhere: blacklistsChecked vs blacklistsListed to avoid misreading counts as totals, and -1 meaning not measured rather than zero. That's genuinely useful, though it omits freshness/rate-limit details.

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-loaded with the verb and the exact fields returned, then the two semantic caveats. Efficient, though the long field enumeration makes it a bit dense; a bulleted structure would scan better.

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?

No output schema exists, so the description carries the return-value burden and largely does it: it enumerates the status fields and explains the two ambiguous value conventions. It could still say what a mailbox-scoped result looks like and what 'recent runs' means in terms of time window.

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 correctly adds no parameter content, and instead spends its words on output 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?

States a specific verb (returns) and resource (latest health check for every connected mailbox) with concrete scope: SPF, DKIM, DMARC, MX, blacklists, placement, health score. Distinguishable from siblings like get_sender_email_dns and get_inbox_placement_run, which cover subsets.

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?

Implied usage: it's the aggregate health-check tool, so an agent would pick it when needing a full mailbox reputation snapshot. But it never says when to prefer this over get_sender_email_dns or get_inbox_placement_run, nor whether it must be called before certain mutations. Context is implied, not explicit.

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