mailX tools

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

Annotations already provide readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, covering safety and idempotency. The description adds context about BIMI's purpose ('display their logo next to authenticated emails in supporting email clients'), which is useful behavioral insight beyond annotations, though it doesn't detail rate limits or specific error conditions.

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: the first states the tool's purpose clearly, and the second provides helpful background on BIMI. It is front-loaded with the core function and avoids unnecessary details, making it efficient and easy to understand.

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 tool's low complexity (1 parameter, no output schema) and rich annotations covering key behavioral traits, the description is mostly complete. It explains what BIMI is and the tool's purpose, but could improve by mentioning output format or error handling, though not strictly required with annotations present.

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%, with the parameter 'domain_name' fully documented in the schema. The description does not add any parameter-specific details beyond what the schema provides, such as format examples or validation rules, so it meets the baseline for high schema coverage.

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 clearly states the specific action ('Check if a domain has a valid BIMI DNS record') and the resource involved ('domain'), distinguishing it from sibling tools like dns_lookup or txt_lookup by focusing specifically on BIMI records. It also explains what BIMI is, providing additional 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 implies usage by mentioning 'BIMI allows brands to display their logo next to authenticated emails', suggesting it's for email authentication purposes. However, it lacks explicit guidance on when to use this tool versus alternatives like dkim_check or dmarc_check, or any prerequisites or exclusions.

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