chaimp-mcp-rcw

A small Model Context Protocol (MCP) server for the Revised Code of Washington (RCW) — Washington State statutes. Built as a learning project: a stdio MCP server in TypeScript that Claude Code (or any MCP client) can call.

Tools

Note on search

Washington exposes no public full-text RCW search API. search matches citations, not keywords — "assault" returns nothing, "9A.36" returns the sections in that chapter. Use it to discover cites, then pass them to get_section.

Related MCP server: cpl-mcp

Data sources (all public, read-only, no keys)

• Section text: https://app.leg.wa.gov/RCW/default.aspx?cite=<CITE> (HTML, parsed with cheerio)

• Cite lookup: https://lawdoccitelookup.leg.wa.gov/v1/rcw/<query>/<limit> (JSON)

• Affecting bills: https://wslwebservices.leg.wa.gov/rcwciteaffectedservice.asmx operation GetLegislationAffectingRcwCite (SOAP 1.1)

Setup

git clone https://github.com/RetiredOnMyTerms/rcw-mcp.git
cd rcw-mcp
npm install
npm run typecheck     # tsc --noEmit
npm run smoke         # hit all three data sources, print results

Add to Claude Code

Run these from the repo root — $(pwd) / $(Get-Location) fills in the absolute path, so nothing is machine-specific.

Run source directly with tsx (no build step):

# macOS / Linux / Git Bash
claude mcp add rcw --scope user -- npx tsx "$(pwd)/src/index.ts"

# Windows PowerShell
claude mcp add rcw --scope user -- npx tsx "$(Get-Location)\src\index.ts"

Or build and point at the compiled output:

npm run build
claude mcp add rcw --scope user -- node "$(pwd)/dist/index.js"

See INSTALL.md for full details and other MCP clients.

Then in a Claude Code session:

• "Get RCW 9A.36.021" → get_section

• "What RCW sections are in chapter 42.56?" → search

• "What bills in 2007-08 affected RCW 9A.36.021?" → cite_affected

Inspect standalone

npm run inspector     # opens the MCP Inspector against the server

Layout

src/
  index.ts            MCP bootstrap: registers the 3 tools, stdio transport
  http.ts             fetch wrapper (User-Agent, timeout, normalized errors, SOAP POST)
  cache.ts            in-memory TTL cache
  tools/
    getSection.ts     scrape + parse a section page (cheerio)
    search.ts         cite-lookup JSON client
    citeAffected.ts   SOAP call + XML parse (fast-xml-parser)
scripts/
  smoke.ts            direct end-to-end test of all three tools

Notes / limitations

• Scraper selectors track the current app.leg.wa.gov markup; if the site changes, get_section returns an honest error rather than garbage.

• get_section caches parsed sections in memory for 1 hour (process lifetime).

• All statute content is © the State of Washington; this tool only fetches and formats public pages.

License

MIT © James Whelan. Covers this tool's code only — RCW statutory text is a work of the State of Washington.