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

With no annotations and no output schema, the description carries the full behavioral burden. It usefully enumerates the derived signals (SPF, DMARC, catch-all, likely pattern), which hints at a read-only analysis, but says nothing about rate limits, permissions, latency, or whether results are cached/fresh.

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?

A single tight fragment with no filler, and the enumerated outputs are front-loaded. It is efficiently sized, though the missing verb makes it read as a label rather than a complete instruction.

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?

Without annotations or an output schema, the description partially compensates by listing what is returned, which is genuinely helpful. It still omits input format, sibling routing, and any behavioral constraints, leaving gaps for a tool whose structured metadata is entirely empty.

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?

One required parameter ('domain') with 0% schema description coverage. The phrase 'A company's email setup' loosely signals that the input is a company domain, but no format, apex-vs-subdomain, or normalization guidance is provided.

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 is a noun phrase listing returned data (provider, catch-all, SaaS tools, DMARC, patterns) rather than a verb+resource statement of what the tool does. It implies domain-level email reconnaissance and is distinguishable from the email-specific siblings, but the agent must infer the action ('analyze/lookup a domain's email setup').

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?

No when-to-use guidance and no routing relative to siblings find_work_email and verify_email. The agent gets no explicit condition telling it to pick this over per-address tools, though the domain-scoped framing offers a weak implied use case.

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