US Government Open Data MCP

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

The description adds valuable behavioral context beyond the annotations. Annotations only provide readOnlyHint=true, but the description discloses data sources ('Congress.gov API (118th-119th Congress); falls back to clerk.house.gov XML for older congresses'), coverage period ('Coverage: 1990 to present'), and fallback behavior. It doesn't contradict annotations (which correctly indicate read-only access) and provides implementation details that help the agent understand reliability and scope.

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 appropriately sized and front-loaded with the core purpose in the first sentence. Subsequent sentences add necessary context about sources, coverage, parameters, and cross-references without redundancy. While slightly dense, every sentence earns its place by providing distinct, valuable information for tool selection and usage.

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 the tool's moderate complexity (5 parameters, no output schema), the description provides strong contextual completeness. It covers purpose, data sources, temporal coverage, parameter guidance, and cross-referencing with other tools. The main gap is the lack of output schema, but the description compensates by indicating what data is returned ('roll call vote results with member-level party breakdown'). With good annotations and schema coverage, this is nearly 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 the schema already fully documents all 5 parameters. The description adds minimal parameter-specific information beyond the schema: it mentions 'Use year param for historical votes' which slightly elaborates on the year parameter's purpose. However, most parameter semantics are already covered in the schema descriptions, so this meets the baseline for high schema coverage.

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's purpose: 'Get House of Representatives roll call vote results with member-level party breakdown.' It specifies the verb ('Get'), resource ('House of Representatives roll call vote results'), and scope ('member-level party breakdown'). It distinguishes from sibling tools by explicitly naming 'congress_senate_votes' as an alternative for Senate votes.

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 guidance on when to use this tool versus alternatives. It states: 'Cross-reference with: congress_senate_votes (same bill's Senate vote), FEC (congress_member donors via fec_candidate_financials), lobbying_search (who lobbied on the bill), FRED (economic impact 1-3 years after passage). For Senate votes, use congress_senate_votes.' This includes both when to use alternatives and complementary tools for cross-referencing.

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