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

Annotations are all false, so the description carries the full burden. It discloses the auth requirement (dns_token), the non-extending expiry ('the name still disappears 24 hours after it was created'), and a rate limit ('One change per name per 10 seconds'). These are meaningful side effects beyond what the schema provides, and there is no contradiction with 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?

Four sentences, each with a distinct role: action, prerequisite, use case, and side-effect/rate-limit. No redundant wording, and the most important information (action, prerequisite) is front-loaded.

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 mutation tool with an output schema and a 100% covered input schema, the description covers the critical behavioral aspects: what it does, when to use it, the required credential, the expiry non-extension, and the rate limit. It omits error cases, but those are not typically required when schema and annotations already provide structural detail.

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 100% with detailed per-parameter descriptions. The tool description adds no new parameter-level meaning beyond reinforcing that dns_token comes from create_dns_name. Baseline 3 is correct when the schema does the heavy lifting.

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 opens with 'Change the address a temporary DNS name points at,' a specific verb+resource statement that clearly differentiates the tool from its siblings (create_dns_name, delete_dns_name, read_dns_name). The title and description align and no ambiguity remains about what operation is performed.

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?

It provides an explicit trigger: 'Use it when the machine behind the name moved and you would rather keep the name than hand out a new one.' It also names the prerequisite dns_token from create_dns_name. While it doesn't explicitly contrast with delete_dns_name or read_dns_name, the use case is clear enough for an agent to route correctly.

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