Repoint a hostname

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

Annotations already declare readOnlyHint=false and idempotentHint=true. The description adds meaningful non-obvious behavior: IPv4/IPv6 changes are allowed but public/private crossings are refused due to DNS rebinding. This gives agents the key failure cases without contradicting 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?

The action is front-loaded and the whole description is about three short sentences. The motivational line about the machine moving is slightly non-essential for invoking the tool, but it is brief and reinforces the purpose.

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 three parameters, no output schema, and annotations covering idempotency, the description plus the fully described schema is sufficient to select and invoke it. It could clarify whether exactly one of ip/target is required and what the response looks like, but these are minor gaps.

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%, so the baseline is 3. The description adds value by constraining the ip parameter (IPv4/IPv6 changes are permitted; public/private crossing is not), which is absent from the schema's simple 'The new address.' description. The target parameter is only covered by the schema, but its 'instead' wording is sufficient.

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 a specific verb + resource: 'Point an existing hostname at a new address.' It clearly identifies this as the update operation for existing hostnames, distinguishing it from the sibling list/get/mint/diagnose tools.

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 clear context: repointing applies to an existing hostname, and address-class rules are stated explicitly ('Repointing within an address class is free... Crossing between public and private is refused'). It does not explicitly name sibling alternatives or state when-not-to-use, so it stops short of 5.

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