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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-schema information: the call costs $0.005 USDC via x402, which is material to an agent deciding whether to invoke it, plus the US-only coverage constraint. It stops short of describing latency or failure behaviour.

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-loads the core purpose, then the metric list, then the price. The long metric enumeration is justified because there is no output schema, so it is the only signal of what is returned. Only minor redundancy in restating geographic levels twice.

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, enumerating the metrics is the right call and makes the return value reasonably predictable. However, with four parameters, zero required, and only 50% schema coverage, the description leaves input semantics (address vs lat/lon, defaults, how level interacts with the request) unexplained.

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 50%: 'level' and 'address' are documented, but 'lat' and 'lon' have no descriptions anywhere. The description echoes the level enumeration (tract, city, county, state, national) and states that an address or place is accepted, but never clarifies lat/lon usage or that all four parameters are optional with 'level' defaulting to all.

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 the resource (demographics), the geographic scope (any US address or place at tract/city/county/state/national level) and enumerates the returned metrics, so the agent knows exactly what comes back. It does not, however, distinguish itself from the sibling tool 'demographics', which an agent must still disambiguate on its own.

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 phrase 'in one call' hints that a single invocation covers all levels, but there is no explicit when-to-use guidance, no statement of when another tool (e.g. the sibling 'demographics') is preferable, and no guidance on choosing address versus lat/lon. An agent gets only implied usage.

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