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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=false, so the mutation and safety profile is covered. The description usefully adds that DNS configuration is a separate, later step, but says nothing about name uniqueness, reversibility, or permissions. Adequate but not rich beyond the annotations.

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?

A single front-loaded sentence with a parenthetical routing hint. No filler, no redundancy, and the primary action precedes the follow-up guidance.

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 no output schema, complete parameter docs, and annotations covering the safety profile, the description is nearly sufficient for correct invocation. Minor gaps remain around success behavior and naming constraints, which keep it from a 5.

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 (name, domain_id, description) are already documented in the schema. The description adds no format, naming-rule, or scoping detail beyond what the schema provides; baseline 3 applies.

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 ('Register a new subdomain name'), which is immediately distinguishable from the sibling verbs delete_subdomain and toggle_subdomain. The parenthetical further clarifies the boundary with add_dns_record, so the agent knows this tool stops at registration.

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 names the follow-up tool and its condition ('use add_dns_record to configure DNS afterwards'), giving a clear sequencing rule. It does not state prerequisites (e.g. domain_id must already exist) or when-not-to-use, so it falls short of a full 5.

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