diff --git a/.github/workflows/comment-trigger.yml b/.github/workflows/comment-trigger.yml
new file mode 100644
index 0000000..2865dab
--- /dev/null
+++ b/.github/workflows/comment-trigger.yml
@@ -0,0 +1,90 @@
+name: Comment Trigger
+
+on:
+  issue_comment:
+    types: [created]
+
+permissions:
+  contents: read
+  pull-requests: write
+  actions: write
+
+jobs:
+  trigger-checks:
+    name: Trigger Checks from Comment
+    if: |
+      github.event.issue.pull_request &&
+      (github.event.comment.body == '/test all' ||
+       github.event.comment.body == '/test-all' ||
+       github.event.comment.body == '/run-all-checks') &&
+      (github.event.comment.author_association == 'OWNER' ||
+       github.event.comment.author_association == 'MEMBER' ||
+       github.event.comment.author_association == 'COLLABORATOR')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Get PR branch
+        uses: actions/github-script@v7
+        id: get-pr
+        with:
+          script: |
+            const pr = await github.rest.pulls.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: context.issue.number
+            });
+            return pr.data.head.ref;
+
+      - name: Add reaction to comment
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.reactions.createForIssueComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              comment_id: context.payload.comment.id,
+              content: 'rocket'
+            });
+
+      - name: Trigger Python CI
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.actions.createWorkflowDispatch({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              workflow_id: 'python.yml',
+              ref: '${{ fromJSON(steps.get-pr.outputs.result) }}'
+            });
+
+      - name: Trigger Go CI
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.actions.createWorkflowDispatch({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              workflow_id: 'go.yml',
+              ref: '${{ fromJSON(steps.get-pr.outputs.result) }}'
+            });
+
+      - name: Trigger TypeScript CI
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.actions.createWorkflowDispatch({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              workflow_id: 'typescript.yml',
+              ref: '${{ fromJSON(steps.get-pr.outputs.result) }}'
+            });
+
+      - name: Comment on PR
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: '🚀 All CI checks triggered! Check the Actions tab for progress.'
+            });
\ No newline at end of file
diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
new file mode 100644
index 0000000..87636b9
--- /dev/null
+++ b/.github/workflows/go.yml
@@ -0,0 +1,80 @@
+name: Go CI
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'go/**'
+      - '.github/workflows/go.yml'
+  pull_request:
+    paths:
+      - 'go/**'
+      - '.github/workflows/go.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  go-lint:
+    name: "Linting"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+      - name: Set up Go
+        uses: actions/setup-go@7a3fe6cf4cb3a834922a1244abfce67bcef6a0c5 # v6.2.0
+        with:
+          go-version: "^1.25"
+      - name: Check formatting
+        run: |
+          cd go/sdk
+          unformatted=$(gofmt -l .)
+          if [ -n "$unformatted" ]; then
+            echo "The following files are not properly formatted:"
+            echo "$unformatted"
+            exit 1
+          fi
+          echo "All Go files are properly formatted"
+      - name: Run Go vet
+        run: |
+          cd go/sdk
+          go vet ./...
+      - name: Run staticcheck
+        uses: dominikh/staticcheck-action@288b4e28bae83c59f35f73651aeb5cab746a06fc # v1.4.0
+        with:
+          install-go: false
+          version: "v0.6.1"
+          working-directory: go/sdk
+
+  go-test:
+    name: "Unit Tests"
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: ["1.23", "1.24", "1.25"]
+    steps:
+      - name: Check out code
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+      - name: Set up Go
+        uses: actions/setup-go@7a3fe6cf4cb3a834922a1244abfce67bcef6a0c5 # v6.2.0
+        with:
+          go-version: ${{ matrix.go }}
+      - name: Test
+        run: |
+          cd go/sdk
+          go test -v ./...
+
+  go-race-test:
+    name: "Race Detection"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+      - name: Set up Go
+        uses: actions/setup-go@7a3fe6cf4cb3a834922a1244abfce67bcef6a0c5 # v6.2.0
+        with:
+          go-version: "1.24"
+      - name: Test with -race
+        run: |
+          cd go/sdk
+          go test -v -race ./...
\ No newline at end of file
diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
new file mode 100644
index 0000000..a1fb6bd
--- /dev/null
+++ b/.github/workflows/python.yml
@@ -0,0 +1,67 @@
+name: Python CI
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'python/**'
+      - '.github/workflows/python.yml'
+  pull_request:
+    paths:
+      - 'python/**'
+      - '.github/workflows/python.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  python-lint:
+    name: "Linting"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+      - name: Install dependencies
+        run: |
+          cd python/sdk
+          pip install -e .
+          pip install ruff mypy
+      - name: Run Ruff formatter check
+        run: |
+          cd python/sdk
+          ruff format --check .
+      - name: Run Ruff linter
+        run: |
+          cd python/sdk
+          ruff check .
+      - name: Run mypy
+        run: |
+          cd python/sdk
+          mypy src/mcp_ext_variants --ignore-missing-imports
+
+  python-test:
+    name: "Unit Tests"
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          cd python/sdk
+          pip install -e .
+          pip install pytest pytest-cov
+      - name: Run tests
+        run: |
+          cd python/sdk
+          pytest -v --cov=src/mcp_ext_variants
\ No newline at end of file
diff --git a/.github/workflows/status-check.yml b/.github/workflows/status-check.yml
new file mode 100644
index 0000000..63d22f4
--- /dev/null
+++ b/.github/workflows/status-check.yml
@@ -0,0 +1,138 @@
+name: Status Check
+
+# This workflow enforces that all relevant CI checks pass based on which files changed.
+# It's the only required status check in branch protection settings.
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  workflow_run:
+    workflows: ["Python CI", "Go CI", "TypeScript CI"]
+    types: [completed]
+
+permissions:
+  contents: read
+  statuses: write
+  checks: write
+  pull-requests: read
+
+jobs:
+  verify-required-checks:
+    name: Verify Required Checks
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request' || github.event.workflow_run.conclusion != 'cancelled'
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Get PR number
+        id: pr
+        run: |
+          if [ "${{ github.event_name }}" == "workflow_run" ]; then
+            PR_NUMBER=$(gh pr list --head "${{ github.event.workflow_run.head_branch }}" --json number --jq '.[0].number')
+            echo "number=$PR_NUMBER" >> $GITHUB_OUTPUT
+          else
+            echo "number=${{ github.event.pull_request.number }}" >> $GITHUB_OUTPUT
+          fi
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Get changed files
+        id: changed-files
+        uses: dorny/paths-filter@v3
+        with:
+          filters: |
+            python:
+              - 'python/**'
+              - '.github/workflows/python.yml'
+            go:
+              - 'go/**'
+              - '.github/workflows/go.yml'
+            typescript:
+              - 'typescript/**'
+              - '.github/workflows/typescript.yml'
+
+      - name: Check required statuses
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const ref = context.payload.pull_request?.head.sha || context.payload.workflow_run?.head_sha;
+
+            // Define required checks per language
+            const requiredChecks = {
+              python: [
+                'Python CI / Linting',
+                'Python CI / Unit Tests (3.10)',
+                'Python CI / Unit Tests (3.11)',
+                'Python CI / Unit Tests (3.12)'
+              ],
+              go: [
+                'Go CI / Linting',
+                'Go CI / Unit Tests (1.23)',
+                'Go CI / Unit Tests (1.24)',
+                'Go CI / Unit Tests (1.25)',
+                'Go CI / Race Detection'
+              ],
+              typescript: [
+                'TypeScript CI / Linting',
+                'TypeScript CI / Unit Tests (20)',
+                'TypeScript CI / Unit Tests (22)'
+              ]
+            };
+
+            // Get changed files from previous step
+            const changedFiles = {
+              python: ${{ steps.changed-files.outputs.python }} === 'true',
+              go: ${{ steps.changed-files.outputs.go }} === 'true',
+              typescript: ${{ steps.changed-files.outputs.typescript }} === 'true'
+            };
+
+            // Collect all required checks based on changes
+            let allRequiredChecks = [];
+            for (const [lang, changed] of Object.entries(changedFiles)) {
+              if (changed) {
+                allRequiredChecks = allRequiredChecks.concat(requiredChecks[lang]);
+              }
+            }
+
+            if (allRequiredChecks.length === 0) {
+              console.log('No language files changed, no checks required');
+              return;
+            }
+
+            // Get all check runs for this commit
+            const { data: checkRuns } = await github.rest.checks.listForRef({
+              owner,
+              repo,
+              ref
+            });
+
+            // Verify all required checks have passed
+            const checkStatuses = {};
+            for (const check of checkRuns.check_runs) {
+              checkStatuses[check.name] = check.conclusion;
+            }
+
+            let allPassed = true;
+            let failureMessage = '';
+
+            for (const requiredCheck of allRequiredChecks) {
+              const status = checkStatuses[requiredCheck];
+              if (!status) {
+                allPassed = false;
+                failureMessage += `❌ ${requiredCheck}: Not started\\n`;
+              } else if (status !== 'success') {
+                allPassed = false;
+                failureMessage += `❌ ${requiredCheck}: ${status}\\n`;
+              } else {
+                failureMessage += `✅ ${requiredCheck}: ${status}\\n`;
+              }
+            }
+
+            if (!allPassed) {
+              core.setFailed(`Required checks have not passed:\\n${failureMessage}`);
+            } else {
+              console.log(`All required checks passed:\\n${failureMessage}`);
+            }
\ No newline at end of file
diff --git a/.github/workflows/typescript.yml b/.github/workflows/typescript.yml
new file mode 100644
index 0000000..fba0aa6
--- /dev/null
+++ b/.github/workflows/typescript.yml
@@ -0,0 +1,61 @@
+name: TypeScript CI
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'typescript/**'
+      - '.github/workflows/typescript.yml'
+  pull_request:
+    paths:
+      - 'typescript/**'
+      - '.github/workflows/typescript.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  typescript-lint:
+    name: "Linting"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v6
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: "20"
+      - name: Install dependencies
+        run: |
+          cd typescript/sdk
+          npm install
+      - name: Run TypeScript compiler check
+        run: |
+          cd typescript/sdk
+          npm run build
+      - name: Run ESLint
+        run: |
+          cd typescript/sdk
+          npm run lint
+
+  typescript-test:
+    name: "Unit Tests"
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: ["20", "22"]
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v6
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: Install dependencies
+        run: |
+          cd typescript/sdk
+          npm install
+      - name: Run tests
+        run: |
+          cd typescript/sdk
+          npm test
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index aaadf73..17c097c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,3 @@
-# If you prefer the allow list template instead of the deny list, see community template:
-# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
-#
 # Binaries for programs and plugins
 *.exe
 *.exe~
@@ -30,3 +27,44 @@ go.work.sum
 # Editor/IDE
 # .idea/
 # .vscode/
+
+# Node.js / TypeScript
+node_modules/
+dist/
+*.tsbuildinfo
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+.venv/
+venv/
+ENV/
+.pytest_cache/
+.mypy_cache/
+.ruff_cache/
+htmlcov/
+.coverage
+.coverage.*
+coverage.xml
+*.cover
\ No newline at end of file
diff --git a/README.md b/README.md
index c44bd0c..0afa166 100644
--- a/README.md
+++ b/README.md
@@ -3,3 +3,73 @@
 > #### **Status:** Experimental. This work is for prototyping and feedback only, and is not an accepted or official MCP extension.
 
 This repository provides a multi-language reference implementation of the variants proposal for the Model Context Protocol (MCP), as described in [SEP-2053](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2053).
+
+## Implementations
+
+| Language | Directory | Package | Status |
+|----------|-----------|---------|--------|
+| Go | `go/sdk/` | `github.com/modelcontextprotocol/experimental-ext-variants/go/sdk` | Planned |
+| Python | `python/sdk/` | `mcp-ext-variants` | Planned |
+| TypeScript | `typescript/sdk/` | `@ext-modelcontextprotocol/variants` | Planned |
+
+
+## CI/CD
+
+This monorepo uses **path-based CI workflows** to efficiently test only what changes:
+
+### How It Works
+
+1. **Language-specific workflows** (`python.yml`, `go.yml`, `typescript.yml`)
+   - Only trigger when their language directory or workflow file changes
+   - Run all tests, linting, and checks for that language
+
+2. **Status check workflow** (`status-check.yml`)
+   - Runs on every PR to verify required checks passed
+   - Determines what needs to pass based on which files changed
+   - This is the only required check in branch protection
+
+### Examples
+
+- Change `python/sdk/file.py` → Only Python CI runs → PR requires Python checks to pass
+- Change both Go and TypeScript files → Both CIs run → PR requires both to pass
+- Change only `README.md` → No language CIs run → PR can merge immediately
+
+### Forcing All Checks
+
+To run all language checks regardless of changed files:
+- **In a PR**: Comment `/test all` (only works for repo owners/members/collaborators)
+- **Manually**: Use GitHub Actions UI or CLI to trigger individual workflows
+
+### Adding New Required Checks
+
+1. **Add your check** to the appropriate language workflow (e.g., `python.yml`):
+   ```yaml
+   python-security-scan:
+     name: "Security Scan"
+     runs-on: ubuntu-latest
+     steps:
+       - name: Run security checks
+         run: # your commands here
+   ```
+
+2. **Update the status check** in `.github/workflows/status-check.yml`:
+   ```javascript
+   const requiredChecks = {
+     python: [
+       'Python CI / Linting',
+       'Python CI / Unit Tests (3.10)',
+       // ... existing checks ...
+       'Python CI / Security Scan'  // ← Add your new check
+     ],
+   ```
+
+3. **Submit PR** - Your new check is now required for all relevant changes!
+
+## License
+
+Apache License 2.0 - See LICENSE file for details
+
+## Resources
+
+- [Variants Proposal Specification (SEP-2053)](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2053) - Full specification and design details
+- [Model Context Protocol](https://modelcontextprotocol.io/specification)
diff --git a/conformance/.gitkeep b/conformance/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/go/sdk/README.md b/go/sdk/README.md
new file mode 100644
index 0000000..56d7d0c
--- /dev/null
+++ b/go/sdk/README.md
@@ -0,0 +1,3 @@
+# MCP Variants - Go Implementation
+
+This will contain the Go implementation of the MCP Variants based on [SEP-2053](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2053).
\ No newline at end of file
diff --git a/go/sdk/examples/.gitkeep b/go/sdk/examples/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/go/sdk/go.mod b/go/sdk/go.mod
new file mode 100644
index 0000000..917c7e8
--- /dev/null
+++ b/go/sdk/go.mod
@@ -0,0 +1,3 @@
+module github.com/modelcontextprotocol/experimental-ext-variants/go/sdk
+
+go 1.23.0
\ No newline at end of file
diff --git a/go/sdk/internal/.gitkeep b/go/sdk/internal/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/go/sdk/variants/variant.go b/go/sdk/variants/variant.go
new file mode 100644
index 0000000..c7d3f83
--- /dev/null
+++ b/go/sdk/variants/variant.go
@@ -0,0 +1,6 @@
+// Copyright 2025 The MCP Variants Authors. All rights reserved.
+// Use of this source code is governed by a Apache-2.0
+// license that can be found in the LICENSE file.
+
+// Package variants implements MCP Variants for experimental extensions.
+package variants
diff --git a/go/sdk/variants/variant_test.go b/go/sdk/variants/variant_test.go
new file mode 100644
index 0000000..4962133
--- /dev/null
+++ b/go/sdk/variants/variant_test.go
@@ -0,0 +1,14 @@
+// Copyright 2025 The MCP Variants Authors. All rights reserved.
+// Use of this source code is governed by a Apache-2.0
+// license that can be found in the LICENSE file.
+
+package variants
+
+import "testing"
+
+func TestPlaceholder(t *testing.T) {
+	// Placeholder test to ensure go test runs successfully
+	if false {
+		t.Error("This should not happen")
+	}
+}
diff --git a/python/sdk/README.md b/python/sdk/README.md
new file mode 100644
index 0000000..5840587
--- /dev/null
+++ b/python/sdk/README.md
@@ -0,0 +1,31 @@
+# MCP Variants Python SDK
+
+Python implementation of the Model Context Protocol (MCP) variants framework.
+
+## Installation
+
+```bash
+pip install mcp-ext-variants
+```
+
+## Usage
+
+```python
+from mcp_ext_variants import Variant
+
+# Example usage will be added as the implementation progresses
+```
+
+## Development
+
+```bash
+# Install in development mode
+pip install -e .
+
+# Run tests (when available)
+pytest
+```
+
+## License
+
+Apache License 2.0 - See LICENSE file in the root directory for details.
\ No newline at end of file
diff --git a/python/sdk/pyproject.toml b/python/sdk/pyproject.toml
new file mode 100644
index 0000000..86aa188
--- /dev/null
+++ b/python/sdk/pyproject.toml
@@ -0,0 +1,71 @@
+[project]
+name = "mcp-ext-variants"
+version = "0.1.0"
+description = "Python SDK for Model Context Protocol variants"
+authors = [{name = "The MCP Variants Authors"}]
+readme = "README.md"
+license = {text = "Apache-2.0"}
+requires-python = ">=3.10"
+classifiers = [
+    "Development Status :: 3 - Alpha",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: Apache Software License",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+]
+dependencies = [
+    "mcp>=1.0.0",
+]
+
+[project.urls]
+"Homepage" = "https://github.com/modelcontextprotocol/experimental-ext-variants"
+"Bug Reports" = "https://github.com/modelcontextprotocol/experimental-ext-variants/issues"
+"Source" = "https://github.com/modelcontextprotocol/experimental-ext-variants"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/mcp_ext_variants"]
+
+[tool.ruff]
+line-length = 120
+target-version = "py310"
+
+[tool.ruff.lint]
+select = [
+    "E",      # pycodestyle
+    "F",      # pyflakes
+    "I",      # isort
+    "UP",     # pyupgrade
+    "C4",     # flake8-comprehensions
+    "PERF",   # Perflint
+]
+
+[tool.ruff.lint.per-file-ignores]
+"__init__.py" = ["F401"]  # Allow unused imports in __init__.py
+
+[tool.ruff.format]
+quote-style = "double"
+indent-style = "space"
+
+[tool.mypy]
+python_version = "3.10"
+warn_return_any = true
+warn_unused_configs = true
+disallow_untyped_defs = true
+ignore_missing_imports = true
+
+[tool.pyright]
+typeCheckingMode = "basic"
+include = ["src/mcp_ext_variants", "tests"]
+venvPath = "."
+venv = ".venv"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+python_files = ["test_*.py", "*_test.py"]
+addopts = "--strict-markers --verbose"
\ No newline at end of file
diff --git a/python/sdk/src/mcp_ext_variants/__init__.py b/python/sdk/src/mcp_ext_variants/__init__.py
new file mode 100644
index 0000000..87c3dc4
--- /dev/null
+++ b/python/sdk/src/mcp_ext_variants/__init__.py
@@ -0,0 +1,11 @@
+# Copyright 2025 The MCP Variants Authors. All rights reserved.
+# Use of this source code is governed by a Apache-2.0
+# license that can be found in the LICENSE file.
+
+"""
+MCP Variants Python SDK
+
+Implements experimental MCP Variants for extended functionality.
+"""
+
+__all__: list[str] = []  # Export list will be populated as the SDK develops
diff --git a/python/sdk/src/mcp_ext_variants/py.typed b/python/sdk/src/mcp_ext_variants/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/python/sdk/src/mcp_ext_variants/variant.py b/python/sdk/src/mcp_ext_variants/variant.py
new file mode 100644
index 0000000..df4f03d
--- /dev/null
+++ b/python/sdk/src/mcp_ext_variants/variant.py
@@ -0,0 +1,9 @@
+# Copyright 2025 The MCP Variants Authors. All rights reserved.
+# Use of this source code is governed by a Apache-2.0
+# license that can be found in the LICENSE file.
+
+"""
+Package variants implements experimental MCP Variants for extended functionality.
+"""
+
+__all__ = []  # Export list will be populated as the SDK develops
diff --git a/python/sdk/tests/__init__.py b/python/sdk/tests/__init__.py
new file mode 100644
index 0000000..c7d5111
--- /dev/null
+++ b/python/sdk/tests/__init__.py
@@ -0,0 +1 @@
+# Tests for mcp-ext-variants
diff --git a/python/sdk/tests/test_variants.py b/python/sdk/tests/test_variants.py
new file mode 100644
index 0000000..0f41f0e
--- /dev/null
+++ b/python/sdk/tests/test_variants.py
@@ -0,0 +1,10 @@
+# Copyright 2025 The MCP Variants Authors. All rights reserved.
+# Use of this source code is governed by a Apache-2.0
+# license that can be found in the LICENSE file.
+
+"""Tests for MCP variants."""
+
+
+def test_placeholder():
+    """Placeholder test to ensure pytest runs successfully."""
+    assert True
diff --git a/typescript/sdk/.eslintrc.json b/typescript/sdk/.eslintrc.json
new file mode 100644
index 0000000..db42afc
--- /dev/null
+++ b/typescript/sdk/.eslintrc.json
@@ -0,0 +1,24 @@
+{
+  "root": true,
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": "latest",
+    "sourceType": "module",
+    "project": "./tsconfig.json"
+  },
+  "plugins": ["@typescript-eslint"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:@typescript-eslint/recommended-requiring-type-checking"
+  ],
+  "env": {
+    "node": true,
+    "es2022": true
+  },
+  "rules": {
+    "@typescript-eslint/explicit-module-boundary-types": "error",
+    "@typescript-eslint/no-explicit-any": "error",
+    "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }]
+  }
+}
\ No newline at end of file
diff --git a/typescript/sdk/.nvmrc b/typescript/sdk/.nvmrc
new file mode 100644
index 0000000..2edeafb
--- /dev/null
+++ b/typescript/sdk/.nvmrc
@@ -0,0 +1 @@
+20
\ No newline at end of file
diff --git a/typescript/sdk/README.md b/typescript/sdk/README.md
new file mode 100644
index 0000000..8277baa
--- /dev/null
+++ b/typescript/sdk/README.md
@@ -0,0 +1,3 @@
+# MCP Variants - TypeScript Implementation
+
+This will contain the TypeScript implementation of the MCP Variants based on [SEP-2053](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2053).
\ No newline at end of file
diff --git a/typescript/sdk/package.json b/typescript/sdk/package.json
new file mode 100644
index 0000000..ea62aa8
--- /dev/null
+++ b/typescript/sdk/package.json
@@ -0,0 +1,56 @@
+{
+  "name": "@ext-modelcontextprotocol/variants",
+  "version": "0.1.0",
+  "description": "TypeScript SDK for Model Context Protocol variants",
+  "type": "module",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "engines": {
+    "node": ">=20"
+  },
+  "scripts": {
+    "build": "tsc",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "lint": "eslint src --ext .ts",
+    "prepublishOnly": "npm run build"
+  },
+  "keywords": [
+    "mcp",
+    "model-context-protocol",
+    "variants"
+  ],
+  "author": "The MCP Variants Authors",
+  "license": "Apache-2.0",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/modelcontextprotocol/experimental-ext-variants.git",
+    "directory": "typescript/sdk"
+  },
+  "bugs": {
+    "url": "https://github.com/modelcontextprotocol/experimental-ext-variants/issues"
+  },
+  "homepage": "https://github.com/modelcontextprotocol/experimental-ext-variants",
+  "files": [
+    "dist",
+    "src",
+    "README.md"
+  ],
+  "peerDependencies": {
+    "@modelcontextprotocol/sdk": "^1.0.0"
+  },
+  "devDependencies": {
+    "@types/node": "^20.0.0",
+    "@typescript-eslint/eslint-plugin": "^6.0.0",
+    "@typescript-eslint/parser": "^6.0.0",
+    "eslint": "^8.0.0",
+    "typescript": "^5.0.0",
+    "vitest": "^2.0.0"
+  }
+}
\ No newline at end of file
diff --git a/typescript/sdk/src/index.ts b/typescript/sdk/src/index.ts
new file mode 100644
index 0000000..eab7d8a
--- /dev/null
+++ b/typescript/sdk/src/index.ts
@@ -0,0 +1,11 @@
+// Copyright 2025 The MCP Variants Authors. All rights reserved.
+// Use of this source code is governed by a Apache-2.0
+// license that can be found in the LICENSE file.
+
+/**
+ * MCP Variants TypeScript SDK
+ *
+ * Implements experimental MCP Variants for extended functionality.
+ */
+
+export * from './variants.js';
\ No newline at end of file
diff --git a/typescript/sdk/src/variants.test.ts b/typescript/sdk/src/variants.test.ts
new file mode 100644
index 0000000..4fdd95c
--- /dev/null
+++ b/typescript/sdk/src/variants.test.ts
@@ -0,0 +1,11 @@
+// Copyright 2025 The MCP Variants Authors. All rights reserved.
+// Use of this source code is governed by a Apache-2.0
+// license that can be found in the LICENSE file.
+
+import { describe, it, expect } from 'vitest';
+
+describe('Variants', () => {
+  it('should be defined', () => {
+    expect(true).toBe(true);
+  });
+});
\ No newline at end of file
diff --git a/typescript/sdk/src/variants.ts b/typescript/sdk/src/variants.ts
new file mode 100644
index 0000000..2a38b2b
--- /dev/null
+++ b/typescript/sdk/src/variants.ts
@@ -0,0 +1,11 @@
+// Copyright 2025 The MCP Variants Authors. All rights reserved.
+// Use of this source code is governed by a Apache-2.0
+// license that can be found in the LICENSE file.
+
+/**
+ * Core variant functionality for MCP
+ *
+ * Experimental variant implementations for extended MCP functionality.
+ */
+
+// Placeholder for variant implementation
\ No newline at end of file
diff --git a/typescript/sdk/tsconfig.json b/typescript/sdk/tsconfig.json
new file mode 100644
index 0000000..95b0198
--- /dev/null
+++ b/typescript/sdk/tsconfig.json
@@ -0,0 +1,22 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "NodeNext",
+    "lib": ["esnext"],
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "strict": true,
+    "isolatedModules": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "moduleResolution": "NodeNext",
+    "resolveJsonModule": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}
\ No newline at end of file
diff --git a/typescript/sdk/vitest.config.js b/typescript/sdk/vitest.config.js
new file mode 100644
index 0000000..bfa5448
--- /dev/null
+++ b/typescript/sdk/vitest.config.js
@@ -0,0 +1,10 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: 'node',
+    include: ['src/**/*.test.ts', 'test/**/*.test.ts'],
+    exclude: ['**/node_modules/**', '**/dist/**']
+  }
+});
\ No newline at end of file