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

Annotations already flag destructiveHint=true, but the description adds real beyond-annotation context: it warns the change affects LIVE DNS resolution and clarifies that only supplied fields are applied (partial PATCH semantics). It still omits auth/permission requirements, 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?

Three tightly packed sentences front-loading purpose, then the safety warning, then the endpoint mapping. No filler, and the most consequential information (live DNS mutation) is prominent.

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 purpose, side effects, and partial-update semantics, and annotations cover the safety profile. Missing only permission/prerequisite details, which keeps it short of full completeness.

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 baseline is 3, but the description adds genuine parameter meaning: "Only the fields you provide are sent" explains partial-update behavior that the schema alone (required zone/record, optional rest) does not spell out. The link to the PATCH endpoint reinforces this.

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 opening sentence states a specific verb and resource ("Update an existing DNS record"), clearly separating it from the create/get/delete/list siblings. It does not explicitly name an alternative tool, but the operation is unambiguous and distinguishable from all siblings.

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?

Usage is only implied by the verb — there is no explicit when-to-use or when-not-to-use guidance, nor a named alternative. The PATCH note hints at the partial-update use case but does not tell the agent when to prefer this over delete+recreate.

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