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

Annotations already cover the safe read-only, idempotent, open-world nature of the call. The description adds useful behavioral context beyond annotations: the exact return contents (address, dates, handles) and the one-query cost. This is enough given the lower burden placed on the description.

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 information-dense: it states the resource, the three key types, the return fields, the mutual-exclusion rule, the relevant sibling alternatives, and the query cost with no filler. Each sentence earns its place.

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 look-up tool with fully documented schema, comprehensive annotations, and an output schema, the description covers everything an agent needs to select and invoke it correctly: keys, return values, exclusions, and cost. Nothing material is missing.

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 schema already documents all three parameters with examples and descriptions, and its top-level description states 'Give exactly one of org_id, asn or poc_handle.' The tool description slightly reinforces this mutual-exclusion constraint but adds no new parameter semantics beyond what the schema provides, so the baseline score 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 identifies the tool as returning the registry record on file, keyed by org ID, AS number, or POC handle, and lists the returned fields (address, registration dates, contact handles). It also distinguishes itself from siblings by giving the conditions under which pwhois_org_search and pwhois_lookup_ip should be used instead.

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 states when to use the tool and explicitly routes to alternatives: use pwhois_org_search to find an org from a name and pwhois_lookup_ip with registry=true for the org behind an IP. It also gives the constraint 'Give exactly one key.'

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