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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false. The description adds meaningful behavioral context beyond those: it inspects only MX/A/CNAME/NS/TXT records and explicitly states 'Non-intrusive — only looks at DNS the domain owner published.' This sets a clear boundary about what the tool does and does not probe.

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 compact and front-loaded: the main purpose appears in the first sentence, output details in the second, and a safety qualifier in the third. Every sentence earns its place with no filler or repetition.

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 single-parameter tool with no output schema, the description adequately explains what the agent should expect back: categorized detections with vendor evidence. It would be slightly stronger with explicit notes on edge cases (e.g., domains with no DNS records), but the described scope and return shape are sufficient for correct invocation.

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% for the single domain parameter, and the schema already documents it with an example ('apple.com'). The description adds no new parameter-level semantics, so the baseline of 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 clearly states a specific action ('Classify a company's public tech footprint') with a defined resource (DNS records) and enumerates concrete output categories (email_provider, hosting_provider, cdn_provider, dns_provider, SaaS via TXT). This distinguishes it from raw DNS sibling tools like dns_lookup or dns_profile, which would return records rather than classified detections.

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 conveys clear use context: use this when you need a company's technology stack inferred from its published DNS. It does not explicitly name sibling alternatives or when-not-to-use conditions, but the 'classify' framing plus non-intrusive DNS-only scope is sufficient directional guidance for selection.

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