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

No annotations are provided, so the description must carry behavioral disclosure; the verb "List" implies a read-only, non-destructive operation, which is useful. However it says nothing about result scope (all NPAs for the state?), ordering, pagination, or what happens when the input has no matching area codes.

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?

Two tight sentences, zero filler, and the core purpose is front-loaded before the usage hint. Every clause 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 simple two-parameter, non-destructive lookup, the definition covers purpose, input semantics, and usage context adequately. A brief hint about the returned data (a flat list of NPAs) would round it out in the absence of an output schema.

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 both parameters are already documented, and the baseline is 3. The description adds only a little semantic framing (state/province/country/territory inputs) beyond the schema's own wording, without format or edge-case detail.

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 plus resource ("List NANP area codes") and scopes the input to a state, province, or NANP country/territory code. It indirectly distinguishes itself from richer siblings by positioning itself as geography-to-NPA mapping, though it never names the siblings it differs from.

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?

"Use for quick geography-to-NPA mapping before deeper area-code or rate-center queries" gives clear situational context and implies the ordering relative to rate-center/area-code tools. It stops short of explicit when-not-to-use exclusions or naming the alternative tools.

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