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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavior: the exact fields returned and a cost disclosure ('Uses LeadBoxer credits per call'), which matters for budgeting. Auth requirements and rate limits remain unstated, keeping it short of a 5.

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?

Front-loaded with the core purpose, then return fields, then usage context, then sibling routing and cost. Four sentences all carry information, though the long parenthetical enumerations of usage types and geo fields are slightly dense.

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?

With no output schema, the description compensates by enumerating return fields (org name, domain, ISP, usage type, geolocation) and discloses credit consumption and the follow-up call to lookup_domain. Nearly complete for a single-parameter lookup; only error/failure behavior is unaddressed.

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?

Only one parameter with 100% schema description coverage; the schema already documents the IPv4/IPv6 example and length bounds. The description restates the IPv4/IPv6 scope but adds no format or edge-case detail beyond the schema, so baseline 3 applies.

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?

States a specific verb and resource ('Identify the organization behind an IPv4 or IPv6 address') and immediately scopes it against the sibling by noting that full firmographics require lookup_domain. An agent can distinguish this from lookup_domain and get_credit_balance without opening any schema.

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?

Gives concrete usage contexts ('server logs, analytics, sign-ups or security events') and an explicit alternative with the condition that selects it ('For full firmographics, call lookup_domain with the returned ipDomain'). No explicit when-not guidance, but the routing decision is clear.

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