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

Annotations already declare readOnly, idempotent, and non-destructive hints. The description adds meaningful behavioral detail: it performs multiple query rounds, compares IP answer sets and TTLs, and ties the behavior to botnet detection. This goes beyond the annotations and helps the agent understand the tool's operational profile without contradicting them.

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 two sentences, front-loaded with the core purpose ('Detect fast-flux DNS behavior'), followed by a clear explanation of the method and rationale. Every sentence contributes, with no filler or repetition of schema/annotation content.

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 presence of an output schema and strong annotations, the description covers the essential context: what the tool does, how it works (multi-round queries), and why it matters. It does not explain return values (covered by output schema) or explicitly address edge cases like cache behavior (covered by parameter descriptions), but it is adequately complete for tool selection and 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 description coverage is 100%, so the parameters (domain, format, rounds, force_refresh) are already well documented. The description adds high-level context (multiple rounds, comparison of IPs/TTLs) but does not explain individual parameters beyond the schema. Baseline 3 is appropriate given the rich schema.

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 'Detect fast-flux DNS behavior' — a specific verb and resource that clearly states the tool's function. It further explains the methodology (multiple rounds of A/AAAA queries, IP rotation check) and distinguishes it from generic DNS tools in the sibling list.

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 clearly implies when to use this tool (when fast-flux detection is needed) and provides context (botnet/malicious infrastructure). However, it does not explicitly name alternative tools or state exclusion conditions (e.g., when a single DNS lookup suffices), leaving some ambiguity among the many sibling DNS-check tools.

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