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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds the useful detail that the lookup targets the _dmarc subdomain, but says nothing about behavior when no record exists (error vs. empty) or about lookup latency, leaving a modest gap.

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 sentence, front-loaded with the verb and resource, with zero filler. Every word earns its place.

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 single-parameter read-only lookup with annotations covering the safety profile and no output schema, the definition is nearly sufficient. The only missing piece is any hint of what the returned record data looks like, which would help an agent decide it has the right 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 0% and the single 'domain' parameter is undocumented in the schema. The phrase 'for a domain' implicitly identifies the parameter's meaning, but provides no format constraints (e.g. no scheme, no subdomain handling) beyond what the schema's maxLength already enforces.

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 (Read) and resource (the DMARC record) plus the exact DNS location (_dmarc), so an agent knows precisely what is fetched. It does not name or contrast with siblings like build_dmarc_record or check_spf, 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?

Usage is only implied: the description says what it reads but never says when to call it versus build_dmarc_record or check_dkim/check_spf, nor does it mention prerequisites such as the domain needing to exist. Adequate for a diagnostic tool, but no explicit context or exclusions.

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