Compare a proposed record set against the live zone

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds value beyond annotations by disclosing the diff-like output breakdown (added, updated, unchanged) and explicitly noting it writes nothing. It does not contradict any annotation, but could still disclose edge-case behavior; the strong annotation baseline makes 4 appropriate.

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 with no wasted words. The first sentence front-loads the core behavior and result categories, while the second gives concise routing guidance. Every word earns its place.

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 read-only diff tool with only 2 required parameters, full schema coverage, and an output schema present, the description fully covers the necessary context: what it does, when to use it, and which sibling tools to avoid. Combined with the annotations and schema, nothing an agent needs to invoke it correctly is missing.

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%, so the schema already documents domainName and records thoroughly, including the allowed TTL values and the 'rdata' field reminder. The description's phrase 'proposed record set' adds minimal semantic value beyond the schema, so the baseline 3 applies.

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 uses a specific verb ('Reports what would change') and resource ('the given records applied to a zone'), and clearly distinguishes itself from siblings by naming eurodns_dns_upsert_record and eurodns_dns_check_zone. It also states the exact output categories (added, updated, unchanged), leaving no ambiguity about what the tool does.

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 description explicitly says to use this tool to review a change before performing it with eurodns_dns_upsert_record, and directs users to eurodns_dns_check_zone for the API's validation report on a full zone document. This is a clear when-to-use directive with concrete alternatives, leaving nothing to inference.

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