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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful context about what is inspected (SVG logo URL, VMC/CMC certificate, DMARC enforcement), but says nothing about failure modes, missing-record behavior, or result interpretation.

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 that leads with the action and resource, then lists the three things examined. No filler, though the trailing 'BIMI needs' phrasing is slightly awkward.

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 one-parameter check with an output schema (so return values need no explanation) and full annotation coverage, the description is adequate but thin. It omits usage context and prerequisites that would help an agent decide between this and the other eight check_* tools.

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% and the single 'domain' parameter is fully documented in the schema ('The domain to check, e.g. example.com. No scheme or path.'). The description adds no parameter detail beyond the schema, so baseline 3 applies.

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 states a specific verb and resource ('Check the domain BIMI record') and elaborates what the record contains: SVG logo URL, VMC/CMC certificate, and DMARC enforcement. This clearly separates it from check_dmarc, check_dkim, and the other DNS checks by resource, though it never names a sibling to contrast against.

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?

There is no explicit when-to-use or when-not-to-use guidance. The mention that it checks 'the DMARC enforcement BIMI needs' hints at a prerequisite relationship but doesn't tell the agent when to reach for check_bimi versus check_dmarc. No alternatives are named despite eight sibling check_* tools.

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