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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds only that results come 'in full detail', without explaining what that detail includes, whether queries hit external DNS, or any rate limits or auth requirements.

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?

Two sentences, front-loaded with purpose, then usage examples keyed to real questions. The enum values are duplicated from the schema, which is mild redundancy but helps scanning.

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 simple two-parameter read-only tool with a fully described schema and clear annotations, the definition covers what an agent needs to select and invoke it. The lack of detail about the 'full detail' return payload is acceptable since no output schema exists but the tool's shape is predictable.

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% and both parameters carry descriptions plus an enum for 'check', so the schema does the heavy lifting. The description merely repeats the enum list already present in the schema and adds no new meaning such as per-check behavior or domain format edge cases.

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 ('Run one Yeevu email check') and resource ('a domain'), and enumerates the eight supported checks (mx, spf, dkim, dmarc, mta_sts, tls_rpt, bimi_record, blacklist). The emphasis on 'one' record implicitly contrasts with check_email_health, though no sibling is named explicitly.

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?

Gives concrete when-to-use guidance with example questions ('is my SPF right?', 'am I blacklisted?') that map directly onto the check enum values. It stops short of stating when not to use it, e.g. pointing to check_email_health for a full-domain assessment.

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