hud_list_counties

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the useful behavioral detail that the output is a list of counties with FIPS codes, and that these FIPS codes are meant to be used as entity_id in other tools. However, it doesn't describe pagination, ordering, or whether all counties are returned at once.

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?

Two sentences with no wasted words. The first sentence states the core function, and the second sentence provides crucial cross-tool guidance. The description is front-loaded and every sentence earns its place.

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 list tool with one well-documented parameter and annotations covering safety, the description is nearly complete. It explains the purpose, the output content, and how the output connects to other tools. The only minor gap is not describing the exact output format or whether the list is sorted, but this is not critical for a simple lookup tool.

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% and the single parameter 'state' is well-described in the schema as a two-letter state code. The description adds the context that the state parameter is used to filter counties, but doesn't add much beyond the schema. Baseline 3 is appropriate.

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 lists counties in a state with their FIPS codes, which is a specific verb and resource. It also distinguishes itself from sibling tools by explaining how the FIPS codes are used as entity_id in related HUD 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 provides clear context for when to use this tool: when you need county FIPS codes for a state to use in hud_fair_market_rents and hud_income_limits. It doesn't explicitly exclude alternatives, but the sibling list shows related HUD tools like hud_list_states and hud_list_metro_areas, and the description's mention of FIPS codes as entity_id gives enough guidance.

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