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

Goes well beyond the annotations (readOnly=false, idempotent=false, openWorld=true) by disclosing the required credential scope (workspace settings write) and the claimed-workspace prerequisite, including the exact failure mode: a sandbox key from self-registration is refused with 403 until claimed. It also warns that storefront-required records cannot be replaced. That is exactly the auth/failure context an agent needs before calling.

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 sentences, front-loaded with the action and followed by naming convention and prerequisites; nearly every clause carries information. The parenthetical record-type list is dense but functional rather than padding.

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 with no output schema, the description covers authorization, prerequisite state, failure behavior, and the non-replaceable-records constraint. It does not say what is returned on success (e.g., a record id), leaving a small gap for an agent that needs to chain a follow-up call.

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%, so every parameter is already documented in the schema, and the description's explanation of 'name' being relative (blog for blog.<domain>, empty for apex) largely restates the schema text. It adds little about ttl or mx_priority beyond what the schema states, 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?

States a specific verb (add) and resource (DNS record) scoped to a domain registered through Last Price, and enumerates realistic use cases (MX for email, TXT for SPF/DKIM/DMARC, CNAME/A for subdomains). This clearly separates it from list_storefront_dns_records, remove_storefront_dns_record, and add_storefront_domain without opening any 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?

Explains when to reach for it — 'to use it for more than the storefront' — with concrete record-type examples, and gives a when-not constraint ('Records the storefront needs cannot be replaced'). It does not name the sibling to use for removal or listing, so the routing is implied rather than explicit.

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