list_counties

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

No annotations are provided, so the description carries the full burden. It states that the tool lists counties with FIPS IDs, which implies a read-only operation. However, it does not disclose any additional behavioral traits such as authentication, rate limits, or reliance on external APIs. The description is minimally adequate.

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 a single, well-structured sentence that front-loads the action and purpose. Every word is necessary, and there is no redundancy or unnecessary detail.

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?

Given the tool's simplicity (one parameter, no output schema) and the presence of sibling tools, the description is complete. It explains what the tool does, why it is useful, and how to use it. The return format (county names and FIPS IDs) is implied, which is sufficient for this context.

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 input schema already provides a description for the single parameter 'state' ('2-letter state code (e.g. 'NY')'). The tool description simply repeats this ('Pass a 2-letter state code'). With 100% schema description coverage, the description adds no new meaning beyond what the schema provides, earning a baseline score of 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?

The description clearly states the verb 'List' and the resource 'counties in a state' with a specific purpose ('so you can look up FMR or income limits by county name'). This distinguishes it from sibling tools like fmr_lookup and income_limits, which perform different actions.

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 explicitly ties the tool to subsequent lookups (FMR, income limits), indicating when to use it. It also specifies the required input format ('Pass a 2-letter state code'), providing clear usage instructions. Although it does not mention when not to use, the context is sufficiently clear given the sibling tools.

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