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

With no annotations, the description carries the full behavioral burden. It usefully discloses the analytic content (SPF, DKIM, DMARC, MX plus registered look-alike domains with mail servers) and the goal of gauging impersonation risk. It does not, however, state that this is a read-only analysis, whether ownership verification is required, expected latency, or what the report returns.

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 tight sentences that front-load what is combined and follow with the risk-assessment purpose. No filler, though the second sentence is more of a value statement than essential invocation detail.

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 one-parameter tool with no output schema or annotations, the description adequately covers scope and intent, and the return value need not be explained absent an output schema. The remaining gap is operational detail (read-only nature, prerequisites), which is minor.

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?

There is a single parameter at 100% schema coverage, so the schema already documents the format and example. The description adds only marginal meaning by emphasizing 'die eigene Domain', reinforcing that the domain should be one you control.

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 names a specific composite scope: DNS-Check (SPF, DKIM, DMARC, MX) combined with the Doppelgänger-Radar. This verb+resource phrasing implicitly distinguishes it from the sibling component tools dns_check and domain_doppelgaenger, so an agent can tell it is the combined report rather than either single check.

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?

Usage is only implied: the reader must infer that this is the full hardening overview versus the narrower dns_check or domain_doppelgaenger siblings. There is no explicit when-to-use or when-not-to-use guidance, no prerequisites, and no alternative named for the case where only one half is needed.

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