TL;DR: claude-faf-mcp is now a Desktop Extension. One file, one click, 32 tools ready. No JSON editing, no terminal, no debugging why Claude Desktop ignores your runtime. The old way is dead.
The Problem We Killed
Every MCP server had the same install story:
- Find
claude_desktop_config.json - Edit JSON by hand
- Get the path wrong
- Restart Claude Desktop
- Debug why it says "Server disconnected"
- Discover Claude Desktop uses its own built-in Node.js (undocumented)
- Fix the path again
- Finally works
That's 8 steps where users give up. We replaced them with one:
Drag. Click. Done.
Desktop Extensions (.mcpb) are Anthropic's new one-click install format. We adopted it before most people knew it existed.
What's in v5.5.0
Desktop Extension (.mcpb)
A 6.2MB bundle that installs with a double-click. Claude Desktop shows the extension page with all 32 tools, per-tool permission controls, and a single toggle to enable/disable. No config files touched.
Full Tool Annotations
Every tool now carries readOnlyHint, destructiveHint, and title annotations. Claude Desktop uses these to sort tools into read-only (15) and write/delete (17) groups with granular permissions. Only faf_clear is marked destructive.
Tilde Path Fix
faf_read and faf_write now expand ~/ paths correctly. Every other tool already did — these were the outliers. Fixed.
Security Cleanup
Removed an unused file (behavioral-instruction.ts) that contained a prompt instruction wrapper pattern. It was never imported, never called — but its presence in the codebase was a liability for directory review. Gone.
Repo Cleanup
27 junk files removed. Test debris, Python artifacts from an early prototype, old WJTTC reports, a 28MB copy of the Anthropic servers monorepo, and victory-lap.txt. The repo now looks like what it is: a production MCP server.
118 Tests. Zero Failures.
We didn't just test the happy path. We tested what breaks MCP servers in the wild.
The adversarial suite was built from real-world MCP vulnerabilities — vulnerablemcp.info, Snyk Labs, Unit42, and Anthropic's own CVEs (CVE-2025-68143 class). Path traversal, resource exhaustion, prompt injection, information leakage, null/unicode/10K-char edge cases. All blocked.
Ship Status
| Check | Status |
|---|---|
| CI/CD | ✓ Green — all jobs passing |
| Build | ✓ Clean (tsc) |
| Jest Suite | ✓ 391/391 passing |
| FAF Score | ✓ 100% Trophy (15/15 slots) |
| WJTTC | ✓ 67/67 Championship Grade |
| Adversarial Security | ✓ 25/25 (5 tiers, real CVE patterns) |
| Total Tests | ✓ 118/118 — zero code failures |
| npm audit | ✓ 0 vulnerabilities |
| Tool Annotations | ✓ 32/32 complete |
| Publish | Status |
|---|---|
| npm | ✓ claude-faf-mcp@5.5.0 live |
| GitHub Release | ✓ v5.5.0 tagged |
| MCP Registry | ✓ v5.5.0 published |
| Desktop Extension | ✓ .mcpb 6.2MB, one-click install |
| Anthropic Directory | ✓ Submitted |
Try It
npm install -g claude-faf-mcp Or download the .mcpb from the GitHub Release and drag it into Claude Desktop.
The Numbers
- v5.5.0 — Released April 15, 2026
- 118/118 — Tests passing (adversarial + WJTTC + live)
- 391/391 — Jest suite passing
- 100% — Trophy score
- 32 — MCP tools (15 read-only, 16 write, 1 destructive)
- 6.2MB — Extension bundle size
- 36,000+ — Downloads across ecosystem
- PR #2759 — Merged in Anthropic MCP ecosystem (October 2025)