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

Annotations already signal read-only, idempotent, and non-destructive behavior. The description adds valuable context by detailing the correlation methodology (SPF, NS, TXT, SRV, CAA) and the insights it produces (vendor email sending, DNS control, integrated services). It goes beyond annotations without contradicting them, earning a solid score.

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 three sentences: main purpose, methodology, and usage guidance. It is front-loaded with the core function, and every sentence contributes meaning without redundancy or fluff.

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 mapping tool with no output schema, the description explains what it does and how, and gives usage boundaries. It does not describe return value structure, but the input schema is rich and sibling differentiation is clear. This is sufficiently complete for an AI to select and invoke it correctly.

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?

The input schema provides 100% coverage for all three parameters (domain, format, force_refresh) with descriptions. The tool description does not add parameter-specific semantics, but the schema already carries the load. 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?

The description opens with a specific verb and resource: 'Map DNS-visible third-party service dependencies for a domain.' It clearly differentiates from siblings by explicitly stating it is 'not for listing who can send email (use check_spf for that).' This makes the tool's purpose unambiguous and distinct.

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?

Provides explicit guidance: 'Use when asked to map third-party or supply-chain dependencies — not for listing who can send email (use check_spf for that).' This gives both positive and negative usage context and names an alternative tool, satisfying the highest bar for usage guidelines.

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