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

Annotations already declare readOnlyHint=false, idempotentHint=true, openWorldHint=true and destructiveHint=false. The description adds real value beyond them: the Premium gate, the fact that the write does not itself activate the domain, and the required external registrar action. It does not describe what happens on a repeat call for the same domain, which the idempotentHint only implies.

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 short sentences, front-loaded with the action and return value, then the limitation, then the follow-up tool. Nothing is wasted and ordering matches how an agent reads it.

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?

With one required parameter, an output schema covering the DNS record return, and full annotation coverage, the description supplies the missing operational context (Premium, two-step flow, registrar action). Only the behavior of re-submitting an existing domain is left to the idempotentHint annotation.

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% and the schema supplies example formats (priya.in, support.priya.in), so the baseline is 3. The description only restates the domain as 'the domain the creator wants in front of their page' without adding format, validation, or root-vs-subdomain guidance beyond the schema.

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 ('Record the domain the creator wants in front of their page and return the DNS record to add'), which is clearly distinct from siblings get_custom_domain, verify_custom_domain, and remove_custom_domain. An agent can tell what it does without opening the 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?

Explicitly scopes the tool: it does not make the domain work, and the creator must add the record at their registrar before verify_custom_domain checks it. This routes the agent to the correct next tool. It lacks an explicit exclusion statement (e.g. what to do if a domain already exists), so it falls short of a 5.

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