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 value by specifying that it checks 'valid SPF records' and explains SPF's purpose, which helps the agent understand the domain-specific validation context beyond the generic 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 front-loaded with the core purpose in the first sentence, followed by a concise explanation of SPF. Both sentences are essential—the first defines the tool's action, and the second provides necessary context—with no redundant or verbose language.

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) and rich annotations, the description is reasonably complete. It explains what SPF is and the tool's purpose, though it could benefit from mentioning output expectations (e.g., returns validation status) since there's no output schema.

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 doesn't 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 specific action ('Check if a domain has a valid SPF DNS record') and resource ('domain'), distinguishing it from siblings like spf_generate (which creates records) and other DNS-related tools. It provides precise technical context about SPF's purpose, making the tool's function unambiguous.

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 SPF validation but doesn't explicitly state when to use this tool versus alternatives like dns_lookup or txt_lookup for broader DNS queries, or spf_generate for creating records. It provides context but lacks explicit guidance on exclusions or comparisons with sibling tools.

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