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

Annotations only declare readOnly=false and destructive=false; the description adds materially more: account-funding requirement, refusal of platform-owned domains, an asynchronous two-call verification pattern, and the name of an output field (ownershipVerification). This is rich behavioral context beyond the structured hints.

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 dense sentences, front-loaded with the core action and benefit, then prerequisites and the fallback flow. Every clause earns its place; the docs link is deferred to the end.

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 mutation with no output schema and only minimal annotations, the description covers prerequisites, refusal conditions, async semantics, the manual verification fallback, and even a referenced return field. Nothing essential for correct invocation is missing.

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%, so the description must carry the load. It clarifies that 'domain' means a domain the user owns and that it must be this project's live connected domain, which adds real meaning, but projectId is never explained and neither parameter's format or relationship is elaborated.

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 and resource ('Set up authenticated sending (DKIM/SPF/DMARC) on a domain') with the goal ('email lands in inboxes'). Clearly distinct from sibling provision_domain, which would be about registering the domain rather than configuring its sending authentication.

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 explicit conditional flows: automatic ownership proof for a live connected domain, otherwise publish the ownershipVerification TXT record and call again. Also states prerequisites (funded account), refusals (lavela-owned domains), and the follow-up action (poll lavela.get_status).

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