email_check_dmarc

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

With no annotations, the description carries the full transparency burden. It discloses analytical behavior by listing the specific tags it parses and the conditions it flags, giving the agent insight into what the check evaluates. However, it does not describe the return format or the behavior for domains with no DMARC record, which is a minor gap.

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 exactly two sentences: first states the action, second adds precise technical scope. No filler or redundancy; every word contributes to 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?

The tool is simple (one parameter, no output schema), and the description covers the core behavior: parsing specific tags and flagging weaknesses. It does not explicitly define the return structure, but the parsing/flagging list makes the output inferable. Missing edge-case behavior (e.g., no record found) is a minor gap.

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?

The input schema has 100% coverage for the single 'domain' parameter with a clear description and example. The tool description adds no further semantic detail beyond stating 'for a domain,' so it does not improve upon the schema. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Check DMARC record for a domain.' It then enumerates the exact DMARC tags parsed (p=, sp=, pct=, rua/ruf, aspf/adkim) and the flags raised (p=none, missing reporting, relaxed alignment), which clearly distinguishes it from sibling SPF/DKIM checks.

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 DMARC validation (e.g., when a domain's email authentication policy needs assessment) but provides no explicit guidance on when to prefer this over alternatives like email_check_spf or email_check_dkim, nor any exclusions or prerequisites.

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