hud_list_counties

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

The annotations provide readOnlyHint=true, so the agent knows this is a read operation. The description adds useful context about the output (counties with FIPS codes) and downstream usage, but it does not disclose other behavioral details such as ordering, pagination, or potential errors. Given the annotation already covers safety, the description provides moderate added value.

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?

The description is two sentences with no unnecessary words. The first sentence states the purpose, and the second provides a practical downstream instruction. It is concise and front-loaded.

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 1-parameter, read-only tool with a complete schema and no output schema, the description is sufficiently complete. It explains what the tool returns (counties and FIPS codes) and how to use the result in related tools, making it self-contained for the agent.

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?

The schema has 100% coverage for the 'state' parameter, including a clear description with examples. The tool description only re-states that it operates on a state without adding any new information about the parameter semantics. The baseline of 3 applies because the schema already explains the parameter.

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?

The description clearly states the tool's function: 'List counties in a state with their FIPS codes.' This uses a specific verb ('List') and resource ('counties in a state'), and distinguishes it from sibling tools like hud_list_states and hud_list_metro_areas by mentioning FIPS codes and the state scope.

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 provides clear usage context by stating that the returned FIPS codes should be used as 'entity_id' in hud_fair_market_rents and hud_income_limits. This tells the agent when this tool is needed, but it does not explicitly contrast it with other listing tools such as hud_list_states or hud_list_metro_areas, so exclusions are not stated.

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