Validate DMARC Record

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, no open world), and the description adds real behavioral context beyond them: no network lookup, the shape of the findings, and the important caveat that policy upgrades are capped at p=quarantine because a pasted record carries no alignment evidence. It also instructs that returned records be presented verbatim.

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?

Front-loaded with the trigger, then the action, then the input constraint and caveats; every sentence carries information. The upgrade/reject-policy aside is slightly long but earns its place by preventing a misuse. Minor density without waste.

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?

For a one-param, no-output-schema validation tool with safety annotations, the description covers trigger, input form, output content (tags, findings, validity) and policy limits. Nothing an agent needs to call it correctly is missing.

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?

Single parameter with 100% schema description coverage, so the schema already documents the 'record' argument and even the not-the-hostname nuance. The description's 'pass the record string itself' reinforces but does not extend the schema, so the baseline of 3 applies.

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?

States a specific verb+resource ('Validate a pasted DMARC record') and enumerates the outputs ('parsed tags, level'd findings, and whether it is valid'). It differentiates from DNS-based siblings by asserting 'No DNS lookup — pass the record string itself,' so an agent can tell it apart from check_record/scan_domain without opening a schema.

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?

Explicit when-to-use trigger: 'Use this when the user pastes a DMARC record and asks whether it is valid, correct or safe.' It also clarifies the input precondition (the record string, not a hostname). It stops short of naming the validation alternatives to avoid (e.g. check_record for live DNS), so it is clear but not exhaustive.

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