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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so safety is covered. The description adds genuine context beyond that: geocoding is performed by the Census Bureau, results are returned per list year, and newer HUD list years are included automatically — behavior an agent could not infer from the schema.

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?

Opens with the core question, then input modes, then return shape — front-loaded and free of filler. Every clause carries information the caller needs.

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 usefully names what comes back (tract, county, ZCTA, metro area, one result per list year). It does not address failure modes such as an un-geocodable address or an out-of-range tract, which would round out a lookup of this type.

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 only 50%, but the description compensates by framing lat+lon as a pair and positioning address, lat/lon, and tract as mutually exclusive alternatives, which the bare schema (zero required params) does not convey. It still doesn't state formats such as coordinate ranges or what happens if multiple modes are supplied.

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 precise question verb-resource pair: whether a site falls in a Qualified Census Tract or Difficult Development Area on HUD's 2027 (and newer) lists. An agent can immediately distinguish this lookup from the sibling calculators and property tools.

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 description enumerates the three accepted input modes (address, lat+lon, tract) and the constraint 'or', which effectively tells the agent how to invoke it. It lacks an explicit statement of when NOT to use it or which sibling to pick for related queries, keeping it just below a 5.

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