email_check_bimi

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

With no annotations provided, the description carries the full burden. It discloses that it validates the presence of specific BIMI fields, adding useful context over the name. However, it does not explain what the tool returns, whether it performs a DNS query, checks syntax validity, or verifies URL accessibility, leaving room for behavioral ambiguity.

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?

The description is two sentences, front-loaded with the main purpose and followed by specific validation details. Every word is necessary; no fluff or tangential information.

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?

The tool is simple (one parameter, no output schema). The description states what it validates but omits any detail about the return format or potential error conditions. Given the lack of annotations and output schema, the description is adequate but not fully complete, as users are left guessing what 'validates' actually yields.

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% with a clear parameter description ('The domain to check BIMI records for'), and the tool description merely repeats 'domain' without adding new semantic detail. This meets the baseline expected for high schema coverage but does not enhance meaning.

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 uses a specific verb ('Check') and resource ('BIMI record for a domain'), and also lists the exact validation criteria (v=BIMI1, l=, a=). This clearly distinguishes it from siblings like email_check_spf and dns_lookup.

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?

The description clearly implies when to use the tool (when checking a domain's BIMI record) but does not provide explicit comparisons or exclusions relative to other email-related checks. Since siblings include many similar email_check_* tools, some explicit guidance would help, but the specificity of the purpose makes it easy to infer.

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