Swift MCP Server (Swift docs + evolution + lint/format)

Quick start (macOS)

• Install dependencies:

  • Node 18+
  • Optional: brew install swift-format swiftformat swiftlint

• In this folder:

  • npm install
  • npm run dev (runs server over stdio)
  • npm run inspector (UI to test tools)

Tools

• swift_docs_search: search TSPL (swift-book) and API Design Guidelines.
• apple_docs_search: search local Apple DocC/docsets (AppKit/SwiftUI/Foundation...), supports filters: frameworks, kinds, topics.
• swift_evolution_lookup: lookup Swift Evolution proposals by ID or keyword.
• swift_lint_run: run SwiftLint if installed.
• swift_format_apply: format Swift source via swift-format or SwiftFormat.
• swift_guidelines_check: heuristic API guideline checks on Swift code.
• swift_update_sync: mirror swift-evolution and swift-book into .cache.
• cocoa_patterns_search: search curated Cocoa patterns (keyboard/focus/window).
• Additional patterns include responder chain basics, child windows, sheets, and menu shortcut conventions.
• hig_search: search local HIG snapshots.
• swift_symbol_lookup: resolve a symbol/selector to Apple doc hits.
• search_hybrid: unified search across Apple DocC, HIG, and patterns.
  • Returns { results, facets } where facets contains sorted counts for sources, frameworks, kinds, topics, and tags.

Tool Usage

• swift_update_sync:

  • Input: none
  • Behavior: mirrors swift-evolution, swift-book, caches API Design Guidelines + HIG pages, seeds sample DocC, and builds indexes (Apple, HIG, patterns, hybrid).
  • Example: node dist/tools/update.js

• swift_docs_search:

  • Input: query: string, limit?: number
  • Sources: TSPL (swift-book) + API Design Guidelines
  • Example: node -e "import('./dist/tools/docs.js').then(m=>m.docsSearch({query:'Optionals',limit:3})).then(console.log)"

• swift_evolution_lookup:

  • Input: query: string, limit?: number
  • Example: node -e "import('./dist/tools/evolution.js').then(m=>m.evolutionLookup({query:'SE-0001',limit:3})).then(console.log)"

• swift_lint_run:

  • Input: path?: string, configPath?: string, strict?: boolean
  • Requires: swiftlint in PATH
  • Example: node -e "import('./dist/tools/lint.js').then(m=>m.lintRun({path:'/tmp/ci.swift'})).then(console.log)"

• swift_format_apply:

  • Input: code: string, swiftVersion?: string, assumeFilepath?: string
  • Requires: swift-format or swiftformat in PATH (server falls back gracefully)
  • Example: node -e "import('./dist/tools/format.js').then(m=>m.formatApply({code:'struct A{}'})).then(console.log)"

• swift_guidelines_check:

  • Input: code: string
  • Heuristics: naming, acronym casing, AppKit/SwiftUI bridge checks (monitors, first responder, child windows, identifiers)
  • Example: node -e "import('./dist/tools/guidelines.js').then(m=>m.guidelinesCheck({code:'class v{}'})).then(console.log)"

• apple_docs_search:

  • Input: query: string, frameworks?: string[], kinds?: string[], topics?: string[], limit?: number
  • Uses MiniSearch index if present; falls back to file scan under .cache/apple-docs
  • Example: node -e "import('./dist/tools/apple_docs.js').then(m=>m.appleDocsSearch({query:'NSWindow',frameworks:['AppKit'],limit:5})).then(console.log)"

• swift_symbol_lookup:

  • Input: symbolOrSelector: string
  • Resolves aliases from content/symbols/aliases.yaml, then queries Apple docs
  • Example: node -e "import('./dist/tools/apple_docs.js').then(m=>m.swiftSymbolLookup('performKeyEquivalent:')).then(console.log)"

• cocoa_patterns_search:

  • Input: queryOrTag: string, limit?: number
  • Searches curated YAML patterns in repo content/patterns/ and .cache/content/patterns/
  • Example: node -e "import('./dist/tools/patterns.js').then(m=>m.cocoaPatternsSearch({queryOrTag:'keyboard',limit:5})).then(console.log)"

• hig_search:

  • Input: query: string, limit?: number
  • Searches .cache/hig snapshots; prefers HTML <title> and canonical links
  • Example: node -e "import('./dist/tools/hig.js').then(m=>m.higSearch({query:'keyboard',limit:5})).then(console.log)"

• search_hybrid:

  • Input: query: string, sources?: ('apple'|'hig'|'pattern')[], frameworks?: string[], kinds?: string[], topics?: string[], tags?: string[], limit?: number
  • Returns: { results, facets } with facet counts
  • Example (class): node -e "import('./dist/tools/hybrid.js').then(m=>m.hybridSearch({query:'NSWindow',sources:['apple'],frameworks:['AppKit'],limit:5})).then(r=>console.log(JSON.stringify(r,null,2)))"
  • Example (method): node -e "import('./dist/tools/hybrid.js').then(m=>m.hybridSearch({query:'performKeyEquivalent',sources:['apple'],frameworks:['AppKit'],kinds:['method'],limit:5})).then(r=>console.log(JSON.stringify(r,null,2)))"

Docker

• Build: docker build -t swift-mcp-server .
• Run: docker run --rm -it swift-mcp-server
• Note: This base image does not include Swift formatters/linters. The server degrades gracefully if binaries are missing. Extend the image if you need them.

Full Docker image (with tools)

• Build: npm run docker:build:full (uses Dockerfile.full)
• Run: npm run docker:run:full
  • Mounts .cache so swift_update_sync persists across runs
• Includes: swift-format, swiftformat, swiftlint built for Linux
• Base: swift:6.0-jammy with Node 20 installed

Notes:

• Building Swift tools from source can take several minutes on first build.
• The runtime image includes the Swift runtime by using the swift:6.0-jammy base.

MCP wiring

• Most MCP clients accept a stdio command. Example:
  • node /ABSOLUTE/PATH/swift-mcp-server/dist/server.js

Cache & Offline

• Run swift_update_sync first to populate .cache with swift-evolution and swift-book. swift_docs_search and swift_evolution_lookup use this cache.
• For Apple/HIG:
  • Place DocC/Dash docsets under .cache/apple-docs/<Framework>/... or run swift_update_sync to fetch a small HIG snapshot into .cache/hig.
  • Curated patterns live in content/patterns/*.yaml and symbol aliases in content/symbols/aliases.yaml.
  • A scheduled workflow refreshes HIG weekly; use workflow_dispatch to run it on-demand.
  • The first successful swift_update_sync will build a MiniSearch index for Apple docs into .cache/index/apple-docs.json.
  • The sync also builds HIG (.cache/index/hig.json) and patterns (.cache/index/patterns.json) indexes for the hybrid search tool.
  • A small sample DocC page is bundled under content/sample-docc/ and is copied into .cache/apple-docs/ by swift_update_sync to enable CI smoke tests and local try-outs.

Contributing Content

• Patterns (content/patterns/*.yaml):

  • Fields: id: string (unique), title: string, tags?: string[], summary?: string, snippet?: string (multiline with |), takeaways?: string[].
  • Keep IDs stable; use kebab-case (e.g., appkit-child-window-attach).
  • After adding, run npm run build && node dist/tools/update.js to reindex.

• Symbol Aliases (content/symbols/aliases.yaml):

  • Map canonical symbol -> list of aliases/selectors (e.g., NSWindow.makeFirstResponder: -> -[NSWindow makeFirstResponder:]).
  • Used by swift_symbol_lookup and improves Apple docs resolution.

• Apple DocC / Dash Docsets (.cache/apple-docs/<Framework>/...):

  • Place DocC JSON or Dash-extracted content under framework subfolders (AppKit/SwiftUI/Foundation/etc.).
  • Run swift_update_sync to index. Bundled samples provide minimal Apple coverage for CI/local dev.

Troubleshooting

• Empty Apple results:

  • Ensure .cache/apple-docs/ contains DocC JSON (run swift_update_sync to seed samples).
  • Check .cache/index/apple-docs.json exists; if not, re-run swift_update_sync.

• Empty hybrid results:

  • Ensure indexes exist in .cache/index/ (apple-docs, hig, patterns, hybrid). Re-run swift_update_sync.
  • Verify filters aren’t too narrow (try without kinds/topics/tags).

• HIG fetch failures:

  • Non-fatal. The sync is best-effort; you can manually place HTML/MD into .cache/hig/ and re-run the sync to index.

• Swift tools missing:

  • Install via Homebrew (brew install swift-format swiftformat swiftlint) or use the full Docker image.

CI / Release Quick Reference

• CI (.github/workflows/ci.yml):

  • macOS runner; caches npm and Homebrew; runs npm ci, build, smoke tests (docs/evolution/format/lint), swift_update_sync, and hybrid smoke tests (class + method).

• Weekly Refresh (.github/workflows/refresh-cache.yml):

  • Scheduled Mondays 06:00 UTC (and manual) to run swift_update_sync and keep caches/indexes fresh.

• Release (.github/workflows/release.yml):

  • Trigger: tag push v*.*.*.
  • Builds dist/ and attaches dist.tar.gz to a GitHub Release.
  • Builds and pushes the full Docker image to GHCR as ghcr.io/<owner>/swift-mcp-server:{tag},latest.
  • Permissions: contents: write, packages: write (uses GITHUB_TOKEN).

Examples

• Hybrid Apple class search (with facets):
  • node -e "import('./dist/tools/hybrid.js').then(m=>m.hybridSearch({query:'NSWindow', sources:['apple'], frameworks:['AppKit'], limit:5})).then(r=>console.log(JSON.stringify(r,null,2)))"
• Hybrid Apple method search with kind filter:
  • node -e "import('./dist/tools/hybrid.js').then(m=>m.hybridSearch({query:'performKeyEquivalent', sources:['apple'], frameworks:['AppKit'], kinds:['method'], limit:5})).then(r=>console.log(JSON.stringify(r,null,2)))" See CONTRIBUTING.md for guidelines on adding content and tools.