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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the result is a scored audit and names the record types checked, but says nothing about live DNS resolution latency, failure modes for unresolvable domains, or whether the score is normalized across record types.

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 front-loaded sentence naming the tool and the record types audited, with the endpoint appended compactly. No filler, though the '(Endpoint: POST /v1/email-dns)' parenthetical adds little for an MCP agent that does not call HTTP directly.

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 two-parameter, no-output-schema tool the description covers what is audited and what is returned at a high level, which is reasonably complete. Gaps remain around the required dkim_selectors semantics and the shape of the scoring breakdown, which nothing else documents.

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 description coverage is 100%, so the schema carries the documentation burden and baseline 3 applies. However, the schema's own descriptions are placeholders ('Array parameter dkim_selectors'), and the description does not clarify that dkim_selectors is required and must be supplied even when no selectors are known.

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?

Uses a specific verb+resource ('Audit MX, SPF 10-lookup limits, DMARC, DKIM, BIMI, and MTA-STS') and enumerates exactly which DNS records are examined, plus the 0–100 score output. It does not distinguish itself from the sibling tinplate_email_dns_generator, so an agent cannot tell from the description alone which of the two to call.

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 implied: you run this when you want a deliverability audit of a domain's email DNS. There is no explicit when-to-use/when-not-to-use guidance and no mention of the closely named tinplate_email_dns_generator sibling, leaving the choice between them to inference.

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