usgs_water_sites

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

Annotations already provide readOnlyHint: true, which discloses the read-only safety profile. The description adds context about the search scope (state, county, site type) but does not mention return format, pagination, or any constraints on combining filters. This is adequate but not rich.

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 concise and front-loaded with the action ('Search for USGS water monitoring sites'). It is two sentences and every sentence earns its place. However, the inclusion of 'hydrologic unit' is an error that detracts from the overall quality, so it loses a point for accuracy.

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 simple search tool with 3 optional parameters and no output schema, the description gives a sufficient overview but lacks details about return values, required filter combinations, or pagination. The mismatch about hydrologic unit also leaves the agent uncertain about available query parameters. It is minimal but not fully complete.

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 description coverage is 100%, so typically this would be a baseline 3. However, the description mentions 'hydrologic unit' as a search criterion but no such parameter exists in the schema. This actively misleads by suggesting a filter that is not available, and it adds nothing beyond what the schema already explains for the existing parameters.

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 'Search for USGS water monitoring sites' with a specific verb and resource, and it distinguishes this from data-retrieval tools like usgs_water_data. However, it mentions searching by 'hydrologic unit' which is not present in the input schema, creating minor ambiguity about the exact capabilities.

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 clear context for when to use this tool (searching for monitoring sites by location/type) but does not explicitly name alternatives or state when not to use it. Siblings like usgs_water_data likely retrieve data for a given site, but no explicit differentiation is given.

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