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

Annotations already declare readOnly/idempotent/openWorld, so safety is covered. The description adds real context beyond them: every missing item comes with the exact record, line or file to add, and 'ready' requires one of four specific website pointers. What remains unsaid is scope of the DNS queries performed and latency.

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?

Two dense sentences with no filler; the readiness rule and fix_lines behavior are front-loaded after a slightly awkward opener ('For a business's own AI'). Nothing is redundant with the schema or annotations.

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?

An output schema exists and parameters are fully documented, so the description only needs to convey intent and pass criteria — which it does by listing the four acceptable pointers and the fix_lines remediation. A first-time agent could call it correctly, though a note on cost/side effects of live DNS lookups would round it out.

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?

Schema coverage is 100%, so the baseline is 3. The description adds a bit by explaining the host fallback relationship to inbox.<domain>, but says nothing about 'target' (the CNAME value) beyond what the schema already documents.

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?

Specific verb+resource: it checks whether an inbox is discoverable from a website/DNS and whether it answers at inbox.<domain>. The readiness criteria (one of four pointers) makes the check concrete. It doesn't name or contrast with siblings like check_business, though, so differentiation is left to inference.

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?

Usage is only implied: it's clearly a diagnostic for a business's inbox setup, and the mention of fix_lines implies use before/after configuring discovery. There's no explicit statement of when to prefer this over check_business or start_inbox, nor prerequisites.

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