mailX tools

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, covering safety and idempotency. The description adds context about DMARC's function (handling emails that fail SPF/DKIM), which is useful but does not disclose additional behavioral traits like rate limits, error handling, or output format. 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 is two sentences that are front-loaded with the core purpose and efficiently explain DMARC's role. Every sentence adds value without redundancy, making it appropriately sized and well-structured for quick understanding.

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 (single parameter, no output schema), rich annotations covering key behavioral aspects, and clear purpose, the description is mostly complete. However, it could benefit from mentioning the return type or what 'valid' entails, but annotations help compensate, making it adequate for the context.

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 without extra value.

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 verb ('Check') and resource ('DMARC DNS record'), specifies the purpose ('valid DMARC record'), and distinguishes from siblings by focusing on DMARC rather than other DNS checks like SPF or DKIM. It provides a concise explanation of what DMARC does, making the purpose specific and well-defined.

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 for verifying DMARC records on domains, which is clear in context, but does not explicitly state when to use this tool versus alternatives like spf_check or dkim_check. It provides some guidance by explaining DMARC's role, but lacks explicit exclusions or named alternatives for sibling tools.

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