email_deliverability_audit

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

With no annotations, the description carries the full burden. It implies a non-mutating audit and discloses the check coverage, but says nothing about authentication requirements, rate limits, runtime, or whether the operation touches live DNS. The 'comprehensive' framing adds context but not operational detail.

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 dense sentences front-load the capability and scope, with compliance context appended. The 'Powered by MailAuthGuard' tagline is mild marketing filler that does not earn its place, keeping it short of a 5.

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 two-parameter read tool it covers what is checked, but with no output schema and no annotations the description should explain what the audit returns (pass/fail per record, scores, remediation hints). That gap leaves it merely adequate.

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 both parameters (domain, dkim_selector with its default) are fully documented in the schema. The description adds no parameter-level detail beyond restating that DNS/DKIM are checked, so the baseline 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 (audit) and resource (email deliverability/DNS/SPF/DKIM/DMARC/BIMI/MTA-STS) scoped to any domain. This is clearly distinguishable from nexus_scrape (scraping) and verify_email_risk (single-address risk).

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?

Mentions the RFC 7208 lookup cap and Google/Yahoo 2024 bulk sender compliance as coverage areas, which hints at a use case, but gives no explicit when-to-use guidance or when to prefer a sibling like verify_email_risk. No prerequisites or exclusions are stated.

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