Blacksmith MCP
An MCP server that connects Claude to your Blacksmith CI data. Query workflow runs, analyze test failures, detect flaky tests, and monitor usage—all through natural conversation.
Why?
Debugging CI failures usually means clicking through dashboards, copying run IDs, and piecing together information across multiple pages. With this MCP, you can just ask:
- "Why did the last CI run fail?"
- "Which tests are flaky this week?"
- "Compare test failures between main and my PR"
- "What's using the most cache storage?"
Claude handles the API calls and gives you actionable insights.
Quick Start
Zero-config if you're logged into Blacksmith in Chrome:
claude mcp add blacksmith -- npx blacksmith-mcp
export BLACKSMITH_ORG="your-org-name"
The MCP automatically extracts your session from Chrome cookies. No manual token copying needed.
Installation
Option 1: Claude Code CLI
claude mcp add blacksmith -- npx blacksmith-mcp
Option 2: Project Configuration
Add to your .mcp.json:
{
"mcpServers": {
"blacksmith": {
"type": "stdio",
"command": "npx",
"args": ["blacksmith-mcp"],
"env": {
"BLACKSMITH_ORG": "your-org-name"
}
}
}
}
Option 3: Global Install
npm install -g blacksmith-mcp
Configuration
Authentication
Automatic (recommended): Log into app.blacksmith.sh in Chrome. The MCP extracts your session cookie automatically.
Manual: Set BLACKSMITH_SESSION_COOKIE environment variable with your session cookie value.
Environment Variables
| Variable | Required | Description |
|---|
BLACKSMITH_ORG | Yes | Your Blacksmith organization name |
BLACKSMITH_SESSION_COOKIE | No | Session cookie (auto-extracted from Chrome if not set) |
Workflow Runs
| Tool | Description |
|---|
list_runs | List workflow runs with filters (status, branch, workflow, actor, PR) |
get_run | Get run details including all jobs |
list_jobs | List jobs for a workflow run |
get_job | Get job details (steps, timing, runner info) |
get_job_logs | Get raw log output for a job |
Test Analytics
| Tool | Description |
|---|
get_job_tests | Get all test results for a job |
get_failed_tests | Get failed tests with full error messages |
get_failures_by_pattern | Group failures by error pattern (e.g., "Cannot read properties") |
compare_test_runs | Compare failures between two runs (find regressions) |
get_flaky_tests | Detect tests that fail intermittently |
get_slow_tests | Find tests exceeding duration threshold |
get_test_history | Track a specific test's pass/fail history |
get_trends | Analyze trends: duration, failure rate, test count |
Usage & Billing
| Tool | Description |
|---|
get_current_usage | Current core usage (active vs max) |
get_invoice_amount | Current billing period amount |
get_usage_summary | Billable minutes vs free tier |
get_cache_stats | Cache size, entries by repository |
get_cache_entries | Detailed cache entries for a repo |
Organization
| Tool | Description |
|---|
list_orgs | List accessible organizations |
get_org_status | Org status (personal, onboarded, region) |
search_logs | Search logs across all jobs |
Example Conversations
Debug a Failed Run
You: Why did the last CI run fail?
Claude: Uses list_runs(status="failure", limit=1) then get_failed_tests
The last run failed with 34 test failures. The main issues are:
- Connection timeout (12 tests) - Tests in
api/ are timing out connecting to the test database
- Undefined property (8 tests) -
user.settings.theme is undefined in the new dark mode code
- Assertion failures (14 tests) - Snapshot mismatches in UI components
Find Flaky Tests
You: Which tests are flaky?
Claude: Uses get_flaky_tests(days=7, min_runs=5)
Found 3 flaky tests:
| Test | Flake Rate | Pattern |
|---|
should handle concurrent requests | 40% (4/10 runs) | Fails on CI, passes locally |
renders loading state | 20% (2/10 runs) | Race condition with setTimeout |
validates auth token | 30% (3/10 runs) | Intermittent network timeout |
Compare Branches
You: Did my PR introduce new test failures?
Claude: Uses compare_test_runs with PR run vs base branch
Your PR introduced 2 new failures:
UserProfile.test.tsx: "Cannot read property 'avatar' of undefined"api/users.test.ts: Expected 200, got 404
5 previously failing tests now pass (nice!).
Development
pnpm install
pnpm build
pnpm dev
npx @modelcontextprotocol/inspector node dist/index.js
Troubleshooting
Session Expired
If you see SESSION_EXPIRED, your Blacksmith session has expired. Simply log back into app.blacksmith.sh in Chrome and retry.
The automatic cookie extraction requires:
- macOS with Chrome installed
- Being logged into Blacksmith in Chrome
- Chrome not running with a locked profile
If it fails, set BLACKSMITH_SESSION_COOKIE manually.
No Organization Set
Run list_orgs to see available organizations, then set BLACKSMITH_ORG to your org name.
API Notes
This MCP uses Blacksmith's internal web API, which is undocumented. The API was reverse-engineered from the Blacksmith web app and may change without notice.
License
MIT
Contributing
Contributions welcome! Please open an issue first to discuss proposed changes.