network_dmarc_record_checker

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

The description describes a read-only DNS lookup, but annotations set readOnlyHint=false, indicating a contradiction. Per rules, a contradiction yields a score of 1. The description otherwise adds useful behavioral context (e.g., rate limits, remote worker, no auth), but the contradiction overrides.

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 well-structured with a clear opening, alternative tool mention, and behavioral details. It is slightly lengthy but every sentence adds value. Front-loading the purpose and sibling differentiation is 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 simplicity (single lookup with 3 parameters) and presence of output schema, the description covers all necessary context: usage scope, behavioral notes (DNS query, remote worker, rate limits, CAPTCHA), and authentication requirements. No gaps are apparent.

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 coverage is 100% with detailed parameter descriptions. The description adds minimal extra meaning (e.g., clarifying action is only lookup and domain is prepended with _dmarc.), but does not significantly enhance understanding beyond the schema.

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 'Look up and validate a domain's DMARC policy by making a live DNS TXT query', specifying the verb, resource, and method. It also explicitly distinguishes from sibling tools like SPF and MX record checkers, making the purpose 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 provides explicit guidance: 'Use network_spf_record_checker instead for SPF/Sender-Policy records or network_mx_record_lookup for mail-server MX records; this tool only resolves DMARC', including an alternative tool mention and scope limitation (single action=lookup).

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