US Government Open Data MCP

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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read operation. The description adds useful context about the different search endpoints and their semantics (e.g., 'Returns all historical members for that seat' for district searches), but doesn't mention rate limits, authentication needs, or pagination behavior beyond the 'limit' parameter in the schema.

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 efficiently structured in two sentences: first stating the purpose and supported filters, then listing the specific endpoint patterns. Every element serves a clear purpose with zero wasted words, and the most important information (what the tool does) is front-loaded.

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 search tool with good annotations (readOnlyHint) and comprehensive schema coverage, the description provides adequate context about search capabilities and endpoint patterns. However, without an output schema, it doesn't describe the structure of returned member data, which would be helpful for understanding results. The description compensates somewhat with endpoint semantics.

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 documents all 7 parameters thoroughly. The description adds some value by showing how parameters combine into different endpoint patterns (e.g., '/member/{stateCode}/{district}'), but doesn't provide additional semantic meaning beyond what's in the schema descriptions. Baseline 3 is appropriate when schema does the heavy lifting.

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 with specific verbs ('Search for members of Congress') and resources ('by state, congress number, district, or get all current members'). It distinguishes itself from sibling tools by focusing on congressional member search, unlike other tools that handle bills, committees, or economic data.

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 on when to use different parameter combinations (e.g., '/member' for all, '/member/{stateCode}' for state filtering), but it doesn't explicitly state when NOT to use this tool or name specific alternatives among siblings. The guidance is operational rather than comparative.

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