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MCP Resources

Resources provide read-only data to AI assistants. Unlike tools (which perform actions), resources simply expose information — configuration files, database records, logs, documentation, or any other data your application manages.

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Registering Resources

Basic Resource
await mcp.registerResource(
    PrismMCPResource(
        uri: "app://config",
        name: "App Configuration",
        description: "Current application configuration settings",
        mimeType: "text/plain"
    ),
    handler: {
        let config = PrismConfig.load()
        return """
        environment: \(config.environment)
        port: \(config.port)
        host: \(config.host)
        """
    }
)

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Resource URIs

Resources are identified by URIs. Use a scheme that makes sense for your domain:
URI PatternUse Case
app://configApplication configuration
db://users/123Database record
file:///path/to/fileFile on disk
log://app/latestApplication logs
docs://api/usersAPI documentation

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Practical Examples

await mcp.registerResource(
    PrismMCPResource(
        uri: "db://schema",
        name: "Database Schema",
        description: "All tables and columns in the database"
    ),
    handler: {
        let tables = try await db.query(
            "SELECT name FROM sqlite_master WHERE type='table'"
        )
        var output = ""
        for table in tables {
            let name = table["name"]
            output += "\n## \(name)\n"
            let cols = try await db.query("PRAGMA table_info(\(name))")
            for col in cols {
                output += "  - \(col["name"]) (\(col["type"]))\n"
            }
        }
        return output
    }
)

await mcp.registerResource(
    PrismMCPResource(
        uri: "log://app/latest",
        name: "Recent Logs",
        description: "Last 100 lines of application logs"
    ),
    handler: {
        let logPath = "/var/log/myapp/app.log"
        let content = try String(contentsOfFile: logPath, encoding: .utf8)
        let lines = content.split(separator: "\n").suffix(100)
        return lines.joined(separator: "\n")
    }
)

await mcp.registerResource(
    PrismMCPResource(
        uri: "docs://api",
        name: "API Documentation",
        description: "REST API endpoints and their descriptions",
        mimeType: "text/markdown"
    ),
    handler: {
        """
        # API Endpoints
        
        ## Users
        - GET /api/users - List all users
        - POST /api/users - Create a user
        - GET /api/users/:id - Get user by ID
        
        ## Posts  
        - GET /api/posts - List all posts
        - POST /api/posts - Create a post
        """
    }
)

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What’s Next

Tools

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Transports

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