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

No annotations; description discloses it never contacts sending IP, treats receiver evidence as unverified, and performs no signature verification, giving a clear safety profile.

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?

Three sentences covering purpose, scope, exclusions, and cost without fluff.

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?

Adequately sets expectations with output hints (prioritized fixes, DNS sources, missing checks) and cost; missing explicit output schema but acceptable given no output schema.

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?

Description maps parameters to their roles (exact-domain DMARC, SPF sending-IP, supplied DKIM selectors, receiver evidence) supplementing missing schema descriptions for domain and dkimSelectors.

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?

Clearly identifies as an email diagnosis bundle covering DMARC, SPF, and DKIM, and explicitly lists exclusions to differentiate from related tools.

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?

Provides context on what it does not handle (signature verification, inherited-policy, inbox claims) helping decide when to use alternatives, but lacks explicit 'when to use' guidance.

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