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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses rich behavioral details: the alignment signal is derived server-side and cannot be asserted by the caller, null record is a valid answer and not a fault, np=reject is added unless already published, and a human must approve before publishing. This goes well beyond what annotations convey.

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 verbose but justified by the tool's conditional logic. It front-loads the trigger conditions and return purpose. However, it repeats the 'scan can justify quarantine at most' idea twice (once in the intro clause and once in the main body), which could be tightened.

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 tool with significant conditional behavior, the description is complete: it covers when to use it, what the output record is, all null-record cases, the meaning of a null result, the np=reject behavior, and the human-approval requirement. The presence of an output schema means return fields need not be enumerated, but the semantic edge cases are fully handled here.

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 already documents the sole parameter 'domain' at 100% coverage, including examples, subdomain support, and punycode normalization. The description adds no new parameter-specific meaning beyond the schema; it references the domain generically. 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 states a specific verb and resource: 'Return a validated DMARC enforcement-upgrade record for a domain.' It also distinguishes this from generic DMARC generation/validation by specifying the exact scenarios (moving off p=none, tightening DMARC, next policy step, post-report below enforcement), which separates it from siblings like generate_dmarc_record and validate_dmarc_record.

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 gives clear when-to-use conditions ('Use this when the user asks how to move DMARC on from p=none...') and when-not conditions ('a scan can justify p=quarantine at MOST', 'p=reject is unlocked only by aggregate-report evidence'). It does not explicitly name alternative sibling tools, so it stops short of full alternative routing, but the guidance is unambiguous.

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