list_metro_areas

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

No annotations are provided, so the description bears the full burden of behavioral disclosure. It indicates the tool returns codes, but does not mention response format, pagination, or data freshness. For a simple enumeration tool, this is adequate but not highly descriptive.

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, front-loaded sentence that efficiently conveys the action, resource, and purpose. No unnecessary words or repetition.

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 zero-parameter listing tool with no output schema, the description is complete. It explicitly connects to sibling tools (FMR, income limits) and explains the value of the output (codes for lookups).

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 has zero parameters and schema description coverage is 100%, so the baseline is 4. The description adds no parameter information because none exist, but it does hint at the response content ('with their codes').

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 action (List), the resource (HUD metropolitan areas), and the purpose (for metro-level FMR and income-limit lookups). It distinguishes itself from sibling tools like fmr_lookup or income_limits by indicating it provides codes for those lookups.

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 states the use case: 'for metro-level FMR and income-limit lookups.' This provides clear context for when to invoke this tool, but it does not mention any exclusions or alternatives. However, as a listing tool, the usage is naturally implied as a prerequisite step.

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