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

Annotations already declare non-readOnly, destructive, idempotent, and openWorld, so the description adds value on top: it discloses the post-call state ('Status starts at pending_dns until DNS and the certificate are ready'), the exact artifacts returned, and quota limits. It does not explain why destructiveHint is set for an add operation (e.g. whether an existing hostname is overwritten), which is a minor gap.

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?

Front-loaded with the action and its return value, then inputs, then state, quotas, and the rejection rule. Every sentence carries information, though the run-on DNS-record clause and the quoted input list make it slightly denser than necessary.

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 mutating tool with no output schema, the description covers the important return values (CNAME/A/ALIAS/TXT records), the resulting state (pending_dns), quota enforcement, and input rejection. Only the reason behind destructiveHint=true remains undisclosed.

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 description coverage is 100%, so all three parameters (slug, token, domain) are already documented with format guidance and token semantics in the schema itself. The description only restates the input list, adding no format or edge-case meaning beyond what the schema provides.

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 ('Attaches a hostname to a slug') and immediately clarifies the output (DNS records to create, split by subdomain vs apex). The reader can distinguish this from siblings like remove_domain, list_domains, and domain_status without opening any schema.

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 usage constraints: token sourcing, plan quotas (Free 1, Hobby 3, Pro 20), and an exclusion ('deed.page names are rejected'). It does not, however, explicitly route the agent to alternatives such as domain_status or remove_domain when the domain already exists.

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