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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds material behavior beyond that: per-call pricing ($0.002 USDC over x402), that failed calls are free, and the two-step quote-then-pay flow. It does not discuss rate limits beyond the free tier or error semantics for malformed addresses, 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 transformation and returned fields, then a tight second paragraph on constraints and pricing; every sentence earns its place. Slightly dense with billing detail, but none of it is filler for an agent that must decide whether to call.

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?

There is no output schema, so the description compensates by enumerating the return fields directly, and it covers the cost/payment behavior an agent needs before invoking a paid tool. For a two-parameter read-only lookup, nothing essential 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?

Schema coverage is 100%, so both parameters are already documented in the schema, and the description's 'US street addresses only (with a house number)' largely restates the schema example's format. The quote/payment flow adds some conceptual framing but no syntax or format detail beyond the schema. 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?

Specific verb+resource: turns a US street address into latitude/longitude, and it goes further by enumerating the derived outputs (standardized address, ZIP, county, FIPS, state, census tract) and naming the data source (US Census Bureau geocoder). No sibling tool competes for this function, so the purpose is unambiguous.

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?

States a clear eligibility constraint ('US street addresses only (with a house number)'), which tells the agent when the tool is not applicable. It also guides the payment workflow (call without `payment` for a quote, first 3 calls free). No alternative tool exists to route against, so the absence of an explicit alternative is not a real gap.

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