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

Without annotations, the description carries the burden of behavioral disclosure. It mentions the need for an API key and the add/update nature of the operation, but it doesn't disclose whether an existing record is overwritten, how long changes take to propagate, or what the API response looks like.

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 two sentences, front-loaded with the primary action and resource. The API key requirement is clearly bracketed with a direct link, and every sentence adds actionable value without redundancy.

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?

With no output schema and no annotations, the description is incomplete for an operationally sensitive mutation. It provides use cases and auth context but omits return values, error behavior, overwrite semantics, and validation details, making it insufficient for a tool that modifies DNS records.

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 low (only 'host' has a built-in description, 20% of parameters). The tool description adds no parameter-specific meaning for 'value', 'type', 'domain', or 'ttl'; it only provides general context about DNS records, leaving the agent to infer format and semantics.

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 a specific action ('Add or update') on a specific resource ('a DNS record for a domain'). It also distinguishes itself from sibling domain-related tools by focusing solely on DNS record management rather than domain purchase, checking, or branding.

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 gives practical context on when to use it ('pointing domains to Vercel, Netlify, or email services'). It doesn't explicitly state when not to use it or name alternatives, but the use cases are clear enough for an agent to select it correctly.

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