Identify HUC12 Watershed

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

Annotations already declare read-only, idempotent, and non-destructive hints, but the description adds substantial behavioral context: the full return JSON structure (finding, count, truncated, features, provenance, query_geometry), error message formats, and the point-vs-polygon intersection behavior. This goes far beyond the annotations and fully discloses side effects (none) and edge cases.

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 core purpose, then efficiently organized into return schema, use cases, and error responses. Every section earns its place; the JSON return block is compact and informative, and there is no redundant filler.

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?

Despite an existing output schema, the description includes a clear return structure and error handling, making it self-contained. It covers usage scenarios, input constraints, output fields, and possible failure modes, leaving no significant ambiguity for an agent selecting or invoking the 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%—all three parameters (lat, lon, geometry) are described in the schema. The description adds value by explicitly stating the mutual exclusivity of lat/lon vs. geometry, listing supported geometry types including BoundingBox, and noting that coordinates must be WGS84. This supplements, rather than repeats, the schema info.

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 specific verb and resource: 'Identify the HUC12 watershed(s) containing/intersecting a geometry' and adds context 'WBDHU12, layer 12'. It clearly distinguishes from sibling tools (waterways, waterbodies, gages) by focusing on watershed identification, reinforced by concrete use-case questions.

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 includes a 'Use when:' section with three example queries, providing clear context for when to invoke the tool. It also explains the differing behavior for point vs. polygon inputs. However, it does not explicitly mention when not to use it or direct users to an alternative sibling tool, so it lacks explicit exclusions.

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