dnstwist lookalike domains

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

Annotations already establish readOnly, openWorld, idempotent, and non-destructive behavior. The description adds valuable behavioral details beyond those: it generates multiple categories of lookalikes (typos, homoglyphs, other TLDs), checks registration status, and returns specific DNS record types (A, MX, NS). This gives the agent a solid expectation of the tool's behavior without repeating the annotations.

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 a single sentence that packs in the action, scope, output, and use case with no filler or redundancy. It is front-loaded with the core functionality and remains easy to parse for an agent scanning multiple tool definitions.

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?

Given the tool's complexity (2 params, 1 required, schema fully covering them, no output schema), the description is largely complete: it states the input, the transformations, the filtering option behavior implied by 'registered', and the DNS records returned. It does not describe output format or pagination, but that is not critical for a simple read-only generator tool.

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%, so the schema already fully documents both the 'domain' and 'registered_only' parameters. The description does not add parameter-level details beyond what the schema provides, but it does not need to. Baseline 3 is appropriate.

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?

Description uses a specific verb ('Generate'), names the resource ('lookalike domains'), and specifies the exact technique (typos, homoglyphs, other TLDs) and output (A, MX, NS records). This clearly distinguishes it from sibling tools like subfinder_subdomain_search or dnsrecon_domain_scan, which focus on subdomains or DNS enumeration rather than typo-squatting detection.

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 explicitly states a use case: 'Useful to spot phishing domains.' This gives the agent clear context for when to invoke this tool over alternatives. It does not explicitly name sibling tools or state when not to use it, so it stops short of a full 5.

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