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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds real value by enumerating the returned fields (GEOID, block group, FIPS, districts, urban area) since there is no output schema. It does not disclose failure behavior when an address fails to match or any rate limits, so it only partially goes beyond the annotations.

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 action and source, followed by a return-field inventory and use cases, with no filler. The return-field list is long but earns its place given there is no output schema.

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 two-parameter read-only lookup with no output schema, the description covers what the tool does, what it returns, and when to reach for it. The remaining gap — no-match/error behavior and precision caveats on geocoding — is minor but leaves the definition slightly incomplete.

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 address formatting and the vintage enumeration are already documented with an example in the input schema. The description adds no meaning beyond that, such as whether 'current' vintage is the default or what the vintages are for — baseline 3.

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 (look up) and resource (census tract) for a US street address, and names the authoritative source (US Census Bureau Geocoder). The sibling get_census_tract_for_coordinates is implicitly distinguished by the address-vs-coordinates input, so an agent can pick between them without opening schemas.

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 closing sentence gives concrete use cases (CRA, LIHTC, opportunity zones, grant eligibility, demographic lookups) which is clear positive guidance. It never explicitly says when NOT to use it or names get_census_tract_for_coordinates as the alternative for coordinate input, so it stops short of a full when/when-not statement.

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