@cyanheads/courtlistener-mcp-server

Public Hosted Server: https://courtlistener.caseyjhand.com/mcp

Overview

US case law and federal court records from CourtListener's 9M+ opinion corpus and its RECAP mirror of PACER. Search opinions and dockets, trace citation networks, resolve citations, look up judges and courts, and read oral argument transcripts and judicial financial disclosures. Runs as a stdio process, a local Streamable HTTP server, or the public hosted endpoint above.

Tools

Resources

The jurisdiction codes are also listed on the jurisdiction parameter of courtlistener_lookup_courts, for clients that don't surface resources.

Prompts

Related MCP server: CourtListener MCP Server

Capability reference

courtlistener_search_opinions tool

• q is required and takes CourtListener field syntax (caseName:"roe v wade", court_id:scotus, judge:"Alito") and AND / OR / NOT; filter by court, filed_after / filed_before, and status, and sort with order_by (score desc default, dateFiled desc, dateFiled asc, citeCount desc); 20 results per page, continued with next_cursor

• Each result carries cluster_id (for courtlistener_get_opinion and courtlistener_get_citations), docket_id, cite_count, a snippet, and opinions[] variants with opinion ID, type, author_id, and local_path; totalCount and effectiveQuery report the match

courtlistener_get_opinion tool

• cluster_id is required; after an outline response, sections: ["opinion_<id>", ...] pulls specific variants, and a name the cluster doesn't have fails as unknown_section

• Cluster metadata (case name, court_id, citations, cite_count, precedential_status, syllabus, posture, docket_id) plus each variant's html_text, plain_text, cites[], download_url, and type_label, the same label courtlistener_search_opinions reports

• kind is full, or outline when the variants overflow the inline budget: the response then lists them as retrievable opinion_<id> sections and keeps the cluster metadata

courtlistener_get_citations tool

• cluster_id is required; direction is cited_by (default, opinions that cite this one) or citing (opinions it cites); optional court and filed_after filters; up to 20 results per page, continued with cursor

• Rows carry cluster_id, court_id, date_filed, cite_count, and snippet; for citing, totalCount counts the unfiltered cited-opinion list, and a filtered page can come back empty while next_cursor is still set

courtlistener_lookup_citation tool

• citation takes one citation or a passage of up to 64,000 characters, and every citation in it resolves; max_court_lookups (default 4, max 20, 0 to skip) caps the docket requests spent on court names

• One matches[] entry per citation, with status (200 one case, 300 several candidates, 400 unrecognized reporter, 404 no match, 429 past the per-request citation cap) and status_label; each of its clusters[] carries cluster_id, docket_id, court_id, and court_resolution (resolved, no_docket, lookup_failed, over_budget, only the last worth retrying with a larger budget)

• Unresolved citations come back as entries, not errors; only text with no parseable citation fails, as not_found. CourtListener meters this endpoint per citation submitted, separately from the per-request limits

courtlistener_search_dockets tool

• q is required and matches case name, docket number, party, and attorney names; party_name (ANDed with q), court, and filed_after / filed_before narrow it; 20 results per page, continued with next_cursor

• Each docket carries docket_id, parties, attorneys, firms, suit_nature, assigned_to / referred_to, and up to 3 sample_documents with is_available and a RECAP filepath_local URL; every response adds a coverage_note on RECAP's partial PACER coverage

courtlistener_get_docket tool

• docket_id is required; entries come 20 per page (CourtListener ignores entries_page_size), walked with entries_page

• Returns docket metadata, total_entries, next_cursor (the next entries_page number), and entries[] whose documents[] carry is_available, page_count, and filepath_local; documents with is_available: false need PACER, and fetching them is not exposed

courtlistener_get_parties tool

• docket_id is required; cursor takes the opaque next_cursor token, not a page number; page_size (max 10) is a request CourtListener may not honor

• Each party carries name, its docket-scoped role, and attorneys[] with name, contact_raw, role_code / role (codes 5–9 mean no longer of record), and date_action; total_parties uses the upstream total when supplied, otherwise counts a single-page result or stays null

courtlistener_search_judges tool

• q is required; filter by appointer (the president's last name), court, and political_affiliation (d, r, i, l, g, u); 20 results per page, continued with next_cursor

• Results carry person_id (for courtlistener_get_judge), political_affiliation and aba_rating as labels rather than codes, and a current_position: the one with no termination date, or the latest-starting when several or none qualify

courtlistener_get_judge tool

• person_id is required; positions are fetched up to a page bound, and truncated with positionsShown reports when a long record ran past it

• Positions (judicial, plus non-judicial roles described by job_title and organization_name), education, political affiliations, ABA ratings, and fjc_id; coded fields keep the raw code beside a label (position_type_label, termination_reason_label, degree_label)

• Dates carry the precision CourtListener recorded in dob_granularity, dod_granularity, date_start_granularity, and date_termination_granularity (year, month, or day)

courtlistener_lookup_courts tool

• Filter by jurisdiction (one of 22 CourtListener codes such as F, FD, FB, S, SA; the full table is in courtlistener://reference/courts), status (active default, inactive, or any), and has_opinion_scraper; live records come 20 per page, walked with page

• courts[] carry id (the court ID every other tool filters on), citation_string, jurisdiction, and scraper flags; all_matching_court_ids lists every match from a bundled snapshot at no request cost, and is empty when more than 1,000 match, so check all_matching_court_ids_complete

courtlistener_search_oral_arguments tool

• q is required and matches case name and transcript text; filter by court and argued_after / argued_before; 20 results per page, continued with next_cursor

• Results carry audio_id (for courtlistener_get_oral_argument), panel_ids (for courtlistener_get_judge), duration_seconds, snippet, and two MP3 links: download_url at the originating court and local_path, CourtListener's durable copy

courtlistener_get_oral_argument tool

• id (an audio_id from a search) is required; sections: ["transcript"] pulls a transcript that an outline response withheld

• Returns panel_ids, duration_seconds, download_url, docket_id, has_transcript, and transcript; kind is outline when the transcript overflows the inline budget. The argument date is not on this record; take it from the search result or the docket

courtlistener_search_financial_disclosures tool

• Filter by judge_id (a person_id) and year; 20 filings per page, continued with cursor. year filters only the fetched page, because CourtListener has no server-side year filter, so keep paging when a page comes back empty with next_cursor set

• Each filing carries disclosure_id, report_type, has_been_extracted, is_amended, pdf_url, per-category counts (investments, gifts, debts, positions, reimbursements, agreements, non-investment and spouse income), and itemized gifts

courtlistener_get_financial_disclosure tool

• disclosure_id is required; categories selects from investments, debts, positions, reimbursements, non_investment_incomes, spouse_incomes, agreements, and gifts (omit for all)

• Returns filing metadata, counts, and the requested line-item rows, with coded value and income columns decoded to dollar ranges (N → $250,001 - $500,000); kind is outline when the full itemization overflows, listing categories by size for a categories re-call

courtlistener://reference/courts resource

• Markdown reference: the 22 jurisdiction codes (rendered from the set courtlistener_lookup_courts validates against), common court IDs, search type codes, the published free-tier rate limits, and the weekly maintenance window (Thursdays 21:00–23:59 PT)

• Static content, cacheable publicly for 24 hours

courtlistener_research_topic prompt

• Arguments: topic required; jurisdiction optional (a court ID such as scotus or ca9); depth optional, overview (default, 3–5 key cases) or deep (adds citation-network traversal and judge lookup)

• Returns one user message laying out the research workflow and a findings template: key cases, precedent trajectory, research gaps

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

CourtListener-specific:

• CourtListener REST API v4: search, opinions and clusters, dockets and entries, parties and attorneys, people and positions, courts, audio, financial disclosures, and citation lookup

• One request queue for the whole process, paced to COURTLISTENER_RATE_LIMIT_PER_MINUTE and COURTLISTENER_RATE_LIMIT_PER_HOUR, so a burst waits instead of failing; a 429 pauses the queue for every waiting call, and a Retry-After is honored within a 45-second wait budget

• Request cost per call: one for most tools; two for courtlistener_get_docket; two or more for courtlistener_get_parties and courtlistener_get_judge (one per extra page of a long roster or career); three for courtlistener_get_opinion and courtlistener_get_citations (plus one per extra page of opinion variants); and for courtlistener_lookup_citation, the lookup plus up to max_court_lookups docket requests

• Input that can't succeed (an empty q, a malformed date, a citation over 64,000 characters, an unknown oral argument section) is rejected before a request is spent

Agent-friendly output:

• Chaining IDs: cluster_id, docket_id, person_id, audio_id, and disclosure_id appear wherever they feed a follow-up call, with field descriptions naming the tool that takes each

• Typed rate-limit errors: reason: "rate_limited" with retryAfter in seconds, whether CourtListener returned the 429 or the queue gave up before sending, in which case the message says no request was spent

• Outlines instead of oversized payloads: courtlistener_get_opinion, courtlistener_get_oral_argument, and courtlistener_get_financial_disclosure return kind: "outline" with named sections to re-call for

• Coverage caveats inline: RECAP coverage_note, court_resolution on citation lookups, truncated on position history, and notices when a page-local filter empties a page that has more pages behind it

Getting started

Public Hosted Instance

A public instance is available at https://courtlistener.caseyjhand.com/mcp — no installation required. Point any MCP client at it via Streamable HTTP:

{
  "mcpServers": {
    "courtlistener-mcp-server": {
      "type": "streamable-http",
      "url": "https://courtlistener.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file. Generate a free API token in your CourtListener account settings.

{
  "mcpServers": {
    "courtlistener-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/courtlistener-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info",
        "COURTLISTENER_API_TOKEN": "your-api-token"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "courtlistener-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/courtlistener-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info",
        "COURTLISTENER_API_TOKEN": "your-api-token"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "courtlistener-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-e", "MCP_TRANSPORT_TYPE=stdio",
        "-e", "COURTLISTENER_API_TOKEN=your-api-token",
        "ghcr.io/cyanheads/courtlistener-mcp-server:latest"
      ]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 COURTLISTENER_API_TOKEN=... bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.4.0 or higher (or Node.js v24+).

• A CourtListener API token from a free account at courtlistener.com. The published free-tier limits are 5 requests per minute, 50 per hour, and 125 per day; actual limits vary by token tier, and Free Law Project membership raises them.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/courtlistener-mcp-server.git

2. Navigate into the directory:

cd courtlistener-mcp-server

3. Install dependencies:

bun install

4. Configure environment:

cp .env.example .env
# edit .env and set COURTLISTENER_API_TOKEN

Configuration

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http

• Run checks and tests:

  bun run devcheck   # Lint, format, typecheck, security
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec

Docker

docker build -t courtlistener-mcp-server .
docker run --rm -e COURTLISTENER_API_TOKEN=your-token -p 3010:3010 courtlistener-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/courtlistener-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic

• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage

• Register new tools, resources, and prompts by importing them in src/index.ts and adding them to the createApp({ tools, resources, prompts }) arrays

• Wrap CourtListener API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.