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name: mcp-security description: Multi-agent and MCP pipeline security with 5-layer defense architecture. Use when building MCP servers, multi-agent systems, or any pipeline that handles user input to prevent prompt injection and ensure proper authorization.

MCP Security Skill

This skill enforces security best practices for MCP servers and multi-agent pipelines.

5-Layer Defense Architecture

1. Input Validation - Sanitize all user inputs
2. Prompt Injection Prevention - Detect and block injection attempts
3. SQL/NoSQL Validation - Prevent query injection
4. User Context Propagation - Maintain identity through pipeline
5. Authorization (RBAC/ABAC) - Enforce access controls

Prompt Injection Prevention

Copy# Always validate and sanitize inputs
def sanitize_input(user_input: str) -> str:
    # Remove potential injection patterns
    # Escape special characters
    # Limit length
    pass

# Never directly concatenate user input into prompts
# ❌ Bad
prompt = f"Process this: {user_input}"

# ✅ Good
prompt = sanitize_input(user_input)
validated_prompt = validate_against_schema(prompt)

User Context Propagation

Copy@dataclass
class UserContext:
    user_id: str
    roles: list[str]
    permissions: list[str]
    tenant_id: str

# Pass context through all pipeline stages
async def process_request(context: UserContext, request: Request):
    # Validate permissions at each step
    if not has_permission(context, "read:data"):
        raise AuthorizationError()

Authorization Patterns

RBAC (Role-Based Access Control)

CopyROLE_PERMISSIONS = {
    "admin": ["read", "write", "delete", "admin"],
    "editor": ["read", "write"],
    "viewer": ["read"],
}

ABAC (Attribute-Based Access Control)

Copydef can_access(user: User, resource: Resource) -> bool:
    return (
        user.department == resource.department
        and user.clearance >= resource.sensitivity
    )

Security Checklist

• All user inputs validated and sanitized
• Prompt injection patterns detected
• SQL queries parameterized
• User context propagated through pipeline
• Authorization checked at each step
• Sensitive data encrypted
• Audit logging enabled