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

With no annotations provided, the description carries the full burden and does so thoroughly. It discloses that the operation is free, publishes DNS records automatically or returns them for manual publication, and warns that takeoverConfirmed=true repoints a foreign MX and moves live email. It also explains the PENDING_DNS state and the need for explicit user consent on conflict.

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?

The description is dense but every sentence adds value. It starts with the core purpose, then pricing and auth, then required/optional parameters, and finally the conflict-handling flow. It is well-structured and front-loaded, with no filler.

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?

The tool has five parameters and no output schema, but the description covers all needed call context: ownership, authentication, DNS mode behavior, follow-up via verifyMailDns, and the consent-and-retry flow for conflicts. An agent has enough information to invoke it correctly and handle failures.

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?

Given only 20% schema description coverage, the description compensates by explaining the meaning of domain (owned), dnsMode (both enum-like options and their consequences), spfMergeConfirmed (replace foreign SPF), and takeoverConfirmed (repoint foreign MX). This goes well beyond the schema, which only describes sessionKey.

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?

The description uses a specific verb and resource: 'Enable email hosting on a domain you own.' It clearly distinguishes the tool from siblings like createMailbox, verifyMailDns, or listMailDomains by defining the core action and its ownership prerequisite.

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?

The description provides clear context: requires authentication, domain ownership, and the domain must use our nameservers for the default dnsMode. It also explains the alternative EXTERNAL_MANUAL flow and how to handle DNS conflicts, though it does not explicitly state when not to use the tool or name sibling alternatives.

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