email_mx

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

Annotations already indicate read-only, non-destructive, idempotent behavior. The description adds significant context beyond that: details on DKIM verification logic (honest evidence, 'verified' vs 'unverifiable'), grading algorithm under different conditions, and the exact return structure. No contradictions 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 concise and packs useful information into a few sentences. It is front-loaded with the primary purpose, then usage, rate limits, and details. While not bullet-pointed, every sentence adds value. Could be slightly more structured but still effective.

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 complexity (multiple DNS records, grading logic) and the presence of an output schema, the description is remarkably complete. It explains the return structure, DKIM status semantics, grading rules, and edge cases (e.g., DKIM unverifiable not penalized). No gaps identified.

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?

Only one parameter ('domain') with 100% schema coverage (description in schema is clear). The description does not add extra parameter semantics beyond stating the domain is used for analysis. Baseline of 3 is appropriate given 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 that the tool analyzes email security components (MX, SPF, DMARC, DKIM) and grades them. It distinguishes itself from domain_report by specifying use cases, making the purpose specific and 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?

Explicitly says when to use (verify email-auth setup, phishing risk) and when not to (full audit via domain_report). Also provides rate limit information (30/hr Free, 500/hr Pro) to set expectations.

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