APIbase

US Congressional Members

congress.legislation.members

Read-onlyIdempotent

Filter and retrieve US Congress members by state, chamber, and congress number. Returns name, party, state, district, and bioguide ID.

Instructions

Search current and historical members of the US Congress. Filter by state, chamber (House/Senate), and Congress number. Returns name, party, state, district, bioguide ID. Source: Congress.gov.

Input Schema

Name	Required	Description
`limit`	No	Number of results (1-25, default 10)
`state`	No	US state code (e.g. CA, TX, NY)
`chamber`	No	Chamber: house or senate
`congress`	No	Congress number. Default: current (119).

Output Schema

Name	Required	Description	Default
`error`	No	Present only when the call failed. Includes error code, message, request_id, and any provider-specific extras.
`result`	No	Tool response payload. Shape varies per tool — consult the tool description and inputSchema. May be an object, array, string, or number depending on the upstream provider response.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.5.0May 1, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description adds value by specifying the source (Congress.gov) and that it covers historical members, which is beyond what annotations provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is extremely concise, consisting of two sentences that front-load the action and key details. No wasted words, every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has an output schema, so return values are already covered. The description provides sufficient context for a search tool: purpose, filters, source, and what is returned. It is complete for its complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3. The description lists filterable fields (state, chamber, congress) but does not explain the 'limit' parameter or provide additional semantics beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool searches current and historical US Congress members, specifies filterable fields (state, chamber, congress), and lists return fields (name, party, state, district, bioguide ID). This distinguishes it from sibling tools like 'congress.legislation.bills' which deal with legislation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

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 the tool (searching Congress members) but does not explicitly mention when not to use it or suggest alternatives. Since sibling tools are for bills, the usage is implied and clear.

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

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