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

The description says the tool works 'without any lookup' and 'reads or computes only', which describes a purely local computation. The annotations set `openWorldHint: true`, implying interaction with an open world of external entities; that directly conflicts with the description's no-lookup/local-only claim. The cost and idempotency details are otherwise useful, but the structured annotation contradicts the stated behavior.

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 definition is front-loaded with the core classification behavior and the use case. It is mostly efficient, but the pricing sentence and the later 'each call is charged, so repeats are not free' restate the same billing point, adding slight redundancy.

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 one parameter, no output schema, and rich annotations, the description does enough: it lists the returned classifications and computed forms, notes that no lookup occurs, and explains billing. It does not describe the exact response shape, so it is not fully complete, but an agent has enough to call it correctly.

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?

There is only one parameter and schema description coverage is 100%, so the schema already carries the parameter documentation. The description adds an example (`ip=10.1.2.3`) and says IPv4 or IPv6 is accepted, which is a small but useful addition beyond the schema's generic 'The IP address'. Baseline 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 states a specific verb and resource: classify an IPv4 or IPv6 address. It enumerates the exact classifications (version, private, loopback, link-local, CGNAT, public) plus computed forms, so an agent can distinguish it from sibling `ip_cidr` without opening either 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?

It gives a concrete use case: triage IPs in logs or allowlists. It also clarifies that no external lookup occurs, which helps separate it from DNS or geolocation tools. It does not explicitly name or exclude the sibling `ip_cidr`, so the routing guidance is clear but not exhaustive.

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