validate_dmarc_record

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

Annotations already indicate read-only, idempotent, non-destructive. The description adds that no DNS lookup is performed and to 'Present any returned record verbatim'. This provides useful behavioral context beyond 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?

Three sentences, front-loaded with purpose, no redundancy. Every sentence adds value: validation outcome, absence of DNS lookup, and guidance on alternatives.

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 good annotations and full schema coverage, the description adequately covers purpose, usage, and behavior. It does not detail the output format, but mentions 'parsed tags, level'd findings, and validity' which is sufficient for a read-only validation tool.

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 a clear description for the 'record' parameter. The description repeats the constraint about not including the hostname, which is already in the schema. An example value is provided, adding minor value.

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 specifies the verb 'validate', the resource 'DMARC record', and the outcomes: 'parsed tags, level'd findings, and whether it is valid'. It distinguishes from siblings like 'upgrade_record' and 'build_dmarc_upgrade'.

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 states 'No DNS lookup' and when to use alternatives: 'upgrade_record previews a stronger policy' and 'p=reject needs a full scan (use build_dmarc_upgrade)'. This provides clear context and exclusions.

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