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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, and the description adds complementary behavioral details without contradicting them: per-address query cost, mixed IPv4/IPv6 support, the 10-hostname limit, and the difference between full and summary result granularity. The quota warning is especially useful for agents planning large batches.

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 but information-dense; every clause adds either a capability, limit, or operational instruction. It opens with the primary use case and then layers constraints in a logical order: modes, limits, sibling preference, type support, hostname cap, and cost. No filler or restatement of the tool name.

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?

The tool's complexity is moderate, but the description covers all agent-facing operational constraints: max batch sizes, default mode, chunking strategy, mixed address types, hostname cap, and cost/quota. An output schema exists, so return-structure details are not the description's job. This description gives enough context to call the tool safely and efficiently.

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%, so the baseline is 3. The description adds real value beyond the schema by explaining the AS/country clustering behavior, the semantic difference between full and summary results, mixed-address support, and the billing/cost model. It does not exhaustively explain every result field, but the output schema already covers structure, so 4 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 'Batch enrichment in one call' and immediately specifies the resource (many addresses) and the enrichment dimensions (origin AS, country, per-address records). It also distinguishes itself from the sibling pwhois_lookup_ip by explicitly recommending this batched variant over repeated calls.

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?

It explicitly tells the agent when to prefer this tool ('Always prefer this over repeated pwhois_lookup_ip calls') and explains the two detail modes with concrete batch limits. It also gives operational guidance for large workloads: chunking ('call again with the next chunk'), the hostname cap, and checking pwhois_my_quota before large batches.

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