Find NHD Point & Line Water Features

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

Beyond the annotations (readOnlyHint, idempotent, etc.), the description adds valuable context: it names the specific NHD layers (NHDPoint layer 2, NHDLine layer 7), explains return fields (gnis_name, ftype/fcode, reachcode), describes the JSON return structure with counts and truncation, and enumerates error responses. This is rich behavioral disclosure, though it could mention data freshness or rate limits.

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 well-structured and front-loaded, starting with a clear purpose, then usage guidance, then output format, and finally errors. It is moderately sized and each sentence adds value. Slight verbosity in the return section could be trimmed, but it is not gratuitous.

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 read-only query tool with no required parameters and a detailed output schema in the description, the tool description is nearly complete. It covers use cases, output format, and error handling. It could be improved by referencing sibling tools for alternatives, but overall it fully equips an agent to select and invoke the tool correctly.

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 descriptions for all four parameters (100% coverage). The description adds meaningful guidance beyond the schema: it stresses using Polygon/BoundingBox for area searches, clarifies that point features include reachcode, and explains the ftype/fcode vs ftype_label/fcode_label distinction, helping the agent interpret results correctly.

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 finds NHD point & line water features, listing specific examples (springs, waterfalls, dams, gates, levees). It uses a specific verb 'Find' and the resource is well-defined, distinguishing it from sibling tools that focus on waterways/waterbodies/gages.

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 explicit 'Use when' examples with concrete queries ('Are there any waterfalls or springs near this point?') and notes the geometric requirement (Polygon or BoundingBox) for point/line features. However, it does not explicitly mention alternative sibling tools when those are more appropriate, so it lacks direct exclusions.

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