Compare a proposed record set against the live zone

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

The description reinforces the readOnlyHint annotation by stating 'without writing anything' and details what the output includes (added, updated, unchanged). While it doesn't explicitly address the openWorldHint or idempotentHint, the behavior is clear enough and consistent with the annotations. No contradictions found.

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 description is extremely concise, consisting of two sentences that pack all essential information without any redundant phrases. It front-loads the core purpose and then distinguishes from the validator tool, making it easy to parse quickly.

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?

Given the tool's simplicity (two parameters, no nested objects) and the presence of output schema information (though not shown), the description sufficiently covers what an agent needs to know: it performs a diff, is read-only, and is intended as a dry-run before upsert. The only minor gap is the lack of explicit detail on return format, but the description's mention of 'added, updated, and unchanged' adequately communicates the output.

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% and the description adds clarity to both parameters: domainName is 'Zone to compare against, e.g. example.com' and records are 'Records the caller intends to end up with.' The phrase 'intends to end up with' clarifies the diff semantics beyond the raw schema, earning a score above the baseline.

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 clearly states the tool's function as a read-only diff: 'Reports what would change if records were applied to the zone domainName — added, updated with old and new values, and unchanged — without writing anything.' It distinguishes itself from sibling tools like eurodns_dns_get_zone (retrieve), eurodns_dns_save_zone (write), and eurodns_dns_upsert_record (modify) by emphasizing it does not write.

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 explicitly advises when to use it: 'Use it to review a change before making it with eurodns_dns_upsert_record,' and when not to: 'It is not the API’s validator: for a per-record validity report on a full zone document use eurodns_dns_check_zone instead.' This provides clear guidance for an agent choosing between similar tools.

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