Email Security Posture

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

Annotations already indicate readOnly, idempotent, openWorld, and non-destructive traits. The description adds significant behavioral context: it performs passive DNS-only probing, tests common DKIM selectors plus custom ones, and outputs a score 0-100 with grades A+-F. 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 three sentences, front-loaded with the core purpose and outputs. Every sentence adds essential information: first sentence covers function and output, second sentence covers use cases, third covers technical details and rate limits. No wasted words.

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?

The description covers the key aspects: what the tool does (SPF, DMARC, DKIM), how it works (passive DNS, custom selectors), output format (score and grades), and rate limits. Since there is an output schema, return values are covered. Minor details like the exact grading scale or finding structure are omitted, but the tool is sufficiently described for correct invocation.

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?

Input schema has 100% description coverage for both parameters. The description reinforces the schema by explaining the purpose of custom selectors and the probing behavior, adding value beyond the schema's basic descriptions. This justifies a score above the baseline of 3.

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 analyzes domain email authentication posture (SPF, DMARC, DKIM) and produces a numeric score with findings. It uses a specific verb ('Analyze') and resource ('domain email authentication posture'), effectively distinguishing it from sibling tools like dns_lookup or domain_report that do not focus on email security.

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 explicitly mentions dual-use for red-team and blue-team, indicates it is passive DNS-only with no SMTP probe, and provides rate limit information. It explains when custom DKIM selectors are needed. While it does not explicitly state when not to use or name alternatives, the context is clear enough for correct tool selection.

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