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

Annotations declare readOnlyHint=false and destructiveHint=false, so the write/non-destructive profile is already covered structurally. The description adds real value beyond that by clarifying additive semantics ('adds a record without touching existing ones'), which is exactly the kind of behavior an agent needs to distinguish this from an upsert. It does not mention auth requirements, error behavior, or what a duplicate name/type would do.

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 short clauses: purpose, additive behavior, and endpoint. Front-loaded with the action, zero filler, and every sentence 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 write tool with full annotation coverage, complete parameter documentation, and no output schema, the description covers purpose and key behavioral nuance. It is slightly thin on usage context and failure modes, but adequate for correct invocation.

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 detailed per-parameter guidance (empty string for apex, record type examples, content meaning). Baseline 3 applies because the schema already does the heavy lifting; the description adds no parameter-level detail beyond what is already documented.

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 and resource ('Create a new DNS record in a zone'), which unambiguously distinguishes it from siblings like dnsimple_update_zone_record, dnsimple_delete_zone_record, and dnsimple_list_zone_records. The API endpoint reference reinforces exactly what operation is performed.

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 word 'Additive' implicitly signals use this when you want to add without modifying existing records, an implied contrast to update_zone_record. But there is no explicit when-to-use vs when-not guidance, no mention of alternatives, and no note about preconditions such as needing an existing zone.

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