US Government Open Data MCP

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

No annotations are provided, so the description carries the full burden. It discloses that the data is aggregated daily means (not real-time), which is useful behavioral context. However, it doesn't mention other important traits like whether this is a read-only operation, potential rate limits, authentication needs, error conditions, or the format/structure of the returned data. The description adds some value but leaves significant gaps for a tool with no annotations.

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 extremely concise (three sentences) with zero wasted words. The first sentence states the core purpose, the second provides critical differentiation from real-time data, and the third offers essential parameter semantics. Every sentence earns its place, and the structure is front-loaded with the most important information.

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?

Given 6 parameters with 100% schema coverage but no annotations and no output schema, the description does an adequate job. It clarifies the data type (historical daily averages vs. real-time) and parameter code meanings, which are crucial for correct usage. However, for a data retrieval tool with no output schema, it doesn't describe what the return data looks like (e.g., time series format, units, potential null values), leaving the agent to infer from the tool name and parameters alone.

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 the baseline is 3. The description adds meaningful context beyond the schema by explaining that parameter codes correspond to specific measurements (e.g., '00060=discharge (cfs)'), which helps interpret the codes. However, it doesn't provide additional guidance on parameter interactions (e.g., how 'period' and 'start_dt' relate) or usage examples beyond what's implied in the schema descriptions.

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 specific action ('Get'), resource ('USGS daily value water data'), and scope ('historical daily averages'). It explicitly distinguishes this tool from real-time data tools, though no direct sibling tools for USGS water data are listed in the provided sibling list. The phrase 'better for trend analysis' further clarifies the intended use case.

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 by contrasting daily aggregated data with real-time instantaneous values and stating it's 'better for trend analysis.' However, it doesn't explicitly mention when NOT to use this tool or name specific alternative tools (e.g., 'usgs_water_data' which might be for real-time data, though not listed as a sibling). The guidance is helpful but lacks explicit exclusions or named alternatives.

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