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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds substantial behavioral context: the beta/experimental status, free credit cost, that results are coverage signals with assessed sample size and confidence (not a computed share), and that they are sorted by assessed_sample_n descending. This goes well beyond annotations and tells the agent exactly what to expect from the response.

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 front-loaded with the beta warning and primary purpose, then flows logically into usage guidance, parameter details, return semantics, and cost. Every sentence carries meaningful information with no redundancy. For a tool with one optional parameter, the length is justified and well-structured.

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?

With a single optional parameter, no required fields, no output schema, and annotations already covering safety, the description fills all remaining gaps: it explains the return format (coverage signal with sample size and confidence), the sorting order, the credit cost, and the proper use case. An agent would have everything needed to call this tool correctly without further inquiry.

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 complete description for the single 'search' parameter, including diacritic-insensitivity, min length, and an example. The description repeats this information almost verbatim, adding no new semantic detail. With 100% schema coverage, the baseline of 3 is appropriate; the description doesn't enhance parameter understanding.

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 opens with a precise verb+resource: 'List the counties for which get_flood_risk can return data', and immediately distinguishes itself from get_flood_risk by noting it is coverage signal only, not actual exposure. This makes it clearly distinct from sibling tools like list_locations or get_flood_risk.

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?

Explicitly states when to use: 'Use this to discover valid location/teryt values for get_flood_risk instead of guessing names.' It also clarifies that each entry is coverage signal only and directs to call get_flood_risk for actual exposure, effectively signaling when not to use it. The optional search filter and sorting behavior are also described, giving an agent complete routing guidance.

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