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

With readOnlyHint=true already covering the safety profile, the description still adds real context: the shape of returned records (provider id, mailCritical flag with examples), the required authorization scope, and the domain-eligibility constraint. It does not discuss pagination or empty-result behavior, but for a bounded read this is beyond what annotations provide.

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?

Two sentences, purpose front-loaded, then return value, then constraints. Every clause carries information an agent can act on and nothing is redundant.

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?

There is no output schema, yet the description compensates by explaining the returned fields (provider id, mailCritical) and their significance, plus auth scope and eligibility limits. For a single-parameter read tool this is sufficient to invoke and interpret the call correctly.

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% with a single, well-documented 'domain' parameter, so the baseline is 3. The description restates the 'on the account' constraint but adds no format, syntax, or filtering detail beyond the schema.

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 ('List') and resource ('live DNS zone records of a domain'), and it is clearly distinguishable from sibling writers like create_dns_record, update_dns_record, and delete_dns_record, as well as from list_domains by scoping to zone records rather than domains.

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?

Gives the operative prerequisite ('Requires the dns:read scope') and a hard precondition ('Only works for domains with live DNS editing'), effectively telling the agent when this will and won't succeed. It stops short of naming alternative tools, but the mention that provider ids are 'needed for update/delete' implicitly routes the agent to the mutation siblings.

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