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

With no annotations, the description carries the full burden, and it does disclose useful behavior: the grading rubric (p=none grades C) and the cost model (x402 price $0.02/call in USDC on eip155:8453). It does not state read-only semantics, error behavior, or that the lookup hits the _dmarc subdomain live, leaving gaps for an unannotated tool.

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?

One tight paragraph that front-loads the fetched content and grading behavior before the usage cue and pricing. The awkward "needs to spoofing policy grade" fragment is the only blemish; nothing is padded.

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 no output schema and no annotations, the description must carry the return-value burden, and it largely does by naming the returned record fields and the grading scale. Missing only minor operational details (live lookup vs cache, failure modes) for a single-parameter read 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%, so the baseline is 3, but the description adds real meaning: the record lives at _dmarc.<domain>, telling the agent to pass the apex domain rather than the _dmarc subdomain. That clarification goes beyond the schema's bare "Domain" label.

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 gives a specific verb+resource (fetch and grade a domain's DMARC record) and enumerates the fields returned (policy, alignment modes, rua/ruf, percentage), so the agent knows exactly what the tool produces. It does not explicitly differentiate itself from closely related siblings like security_spf_check or security_email_security_audit, which keeps it from a 5.

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?

There is a when-to-use cue ("Use this when an agent needs a spoofing policy grade + report destinations"), though the phrasing is garbled. No when-not conditions or named alternatives are given, so the agent must infer that SPF checks belong to a sibling tool.

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