check_dmarc

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, lowering the bar. The description adds valuable behavioral context: 'live' lookup, alignment problems, and exact record to publish. No contradiction 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?

Two sentences, 26 words, front-loaded with the main action and results. Every sentence earns its place with no redundancy.

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?

With only one parameter and no output schema, the description must explain the return value; it does by mentioning alignment problems and the exact record to publish. It also covers the scope ('any domain') and the fact it's a live check, making it complete for the tool's simplicity.

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 for the single 'domain' parameter is 100%, with the schema describing it as 'Domain to check, e.g. example.com'. The description adds a minor nuance that any domain works, but this is more usage guidance than parameter semantics, so 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 uses a specific verb 'Check' with a clear resource ('live SPF, DKIM, and DMARC DNS records') and states the output ('report alignment problems with the exact record to publish'). It also explicitly mentions it works for any domain, distinguishing it from likely sibling tools like verify_domain.

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 clear context: it checks DNS records for any domain and reports alignment issues. However, it does not explicitly name alternative tools or state when not to use this tool, falling short of a fully explicit usage guideline.

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