BIMI Check

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 description's burden is lowered. It adds context about what BIMI is but does not disclose behavioral specifics such as what constitutes 'valid', which DNS record type is queried, or edge-case behavior (e.g., nonexistent domain). No contradiction with annotations.

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 consists of just two sentences: the first states the primary action and the second provides brief background on BIMI. It is front-loaded, concise, and every sentence contributes useful context without excess.

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?

With no output schema, the description does not specify the return value or error behavior, which remains an ambiguity for the agent. However, given the tool's simplicity (one parameter, strong annotations) and the self-explanatory nature of a 'check', the description is minimally adequate for invocation, though not fully complete.

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% for the single required parameter, with domain_name already including an example ('e.g. example.com') and format description. The description repeats the concept of 'domain' without adding any additional semantic detail beyond the schema, so the baseline of 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 uses a specific verb 'Check' and a specific resource 'valid BIMI DNS record', clearly distinguishing it from sibling tools like dkim_check, spf_check, and dns_lookup. It also expands the BIMI acronym to provide helpful context.

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 states the tool's use case: checking if a domain has a valid BIMI record. However, it does not explicitly mention when to use this tool over alternatives or provide exclusions, though the niche nature of BIMI makes the intended use fairly obvious.

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