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

With no annotations, the description carries the full behavioral burden. It usefully flags 'Mutating' and the IDN/suffix resolution restriction referencing dns_record_idn_disabled, but it omits whether unspecified fields are preserved, permission/auth requirements, and reversibility of the change.

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?

Compact and front-loaded: mutating nature and the field list come first, with secondary IDN caveats trailing. Every sentence adds information, though the trailing IDN parenthetical is terse to the point of being cryptic.

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 7-parameter mutation tool with 0% schema coverage, no annotations, and no output schema, the description is only partially sufficient: it clarifies partial-update semantics but leaves required identifiers, permission needs, and return behavior unaddressed.

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 0%, so the description must compensate, and it does name most updatable fields (type/name/content/ttl/disabled). But it omits the two required params (zoneId, recordId) and lists 'meta', which does not appear in the schema — a small inconsistency that leaves real gaps.

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 ('Update') and resource ('DNS records'), scopes it ('one of your'), and enumerates the mutable fields, making it easily distinguishable from siblings like dns_record_create and dns_record_delete. An agent can identify the operation 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?

The 'at least one field' condition is a genuine usage constraint, and the reference to creation-time IDN behavior hints at a related tool. However, no alternatives are explicitly named and there is no when-not-to-use guidance (e.g., use dns_record_delete to remove, dns_record_create to add).

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