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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered; the description still adds value with 'it never changes DNS' and the freshness behavior (in-progress domains re-checked every few minutes) plus the last-check timestamp. It does not cover error behavior for unknown domains or any rate/refresh limits beyond the re-check cadence.

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?

Front-loaded with purpose, then return content, then freshness, then the alternative - a logical order with no filler sentences. It is dense (one long semicolon-delimited clause) but every clause carries information.

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, the description does the work of explaining the return shape (each record group as found or missing, with type/host/value to add), which is exactly what an agent needs. Minor gaps remain around error cases (domain not found) and whether the 'last check' field is always populated.

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% with a single 'domain' param whose example is given in the schema itself; the description adds no format or syntax detail beyond that. Baseline 3 applies when the schema fully carries parameter documentation.

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+resource combination: it retrieves the DNS setup for one domain, and enumerates the record groups returned (MX, SPF, DKIM, DMARC, sending, mail-app). It is clearly distinguishable from siblings like list_dns_records (raw records) and get_setup_summary (account-wide).

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?

Explicitly routes the agent to the alternative: 'For an account-wide summary use get_setup_summary,' giving both the condition (account-wide vs single domain) and the tool to use. The single-domain scope is stated up front.

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