mailX tools

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

Annotations cover key behavioral traits: readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, indicating a safe, repeatable, and flexible read operation. The description adds context by explaining DKIM's purpose, but doesn't disclose additional behaviors like rate limits, error handling, or output format. With annotations providing a solid foundation, the description offers modest value beyond them, warranting an average score.

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 concise and well-structured in two sentences: the first states the tool's purpose, and the second provides background on DKIM. Every sentence adds value, with no wasted words. However, it could be slightly more front-loaded by integrating the DKIM explanation more seamlessly, but it remains efficient overall.

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 (2 parameters, no output schema) and rich annotations, the description is minimally complete. It covers the basic purpose and context but lacks details on output (e.g., what 'valid' means, return format) and usage guidelines. With annotations handling safety and idempotency, the description is adequate but has clear gaps in guiding the agent effectively.

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 clear descriptions for both parameters ('domain_name' and 'dkim_selector'), including examples. The description doesn't add any semantic details beyond the schema, such as explaining selector conventions or domain validation rules. Given the high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't need to.

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 tool's purpose: 'Check if a domain has a valid DKIM (DomainKeys Identified Mail) DNS record for a given selector.' It specifies the verb ('Check'), resource ('DKIM DNS record'), and scope ('domain' and 'selector'). However, it doesn't explicitly differentiate from sibling DNS-related tools like 'dns_lookup' or 'txt_lookup', which could also retrieve DKIM records, so it falls short of a perfect score.

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 provides no guidance on when to use this tool versus alternatives. It explains what DKIM is ('allows the receiver to verify that an email was sent by the domain owner'), but doesn't specify use cases, prerequisites, or comparisons to sibling tools like 'dns_lookup' for general DNS queries or 'dmarc_check' for related email authentication. This leaves the agent without explicit usage instructions.

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