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

Without annotations, the description conveys that this is a read-only check, specifically noting it skips VMC validation and returns specific fields (record, logo URL, authority URL). While it doesn't explicitly state side effects or permissions, the nature of the tool and detailed return info provide adequate behavioral context.

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 core purpose, and every clause adds value. It efficiently explains the tool's scope, speed advantage, and return data without fluff.

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?

Given the simple tool (1 parameter, no output schema), the description is complete: it explains what the tool does, how it differs from bimi_vmc, and what it returns. The agent has enough to decide when to invoke it and what to expect.

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 no additional parameter semantics beyond what the schema already provides; it only reiterates that the domain is checked and gives an example in the schema.

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 explicitly states the verb 'Check' and the resource 'BIMI DNS record for a domain', clearly distinguishing it from bimi_vmc by noting it skips VMC validation. It also lists the exact return values, leaving no ambiguity about the tool's function.

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 names the alternative tool (bimi_vmc) and explains the trade-off: bimi_check is faster because it skips VMC certificate download and validation. This gives clear guidance on when to use this tool versus the sibling.

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