DynamoDB MCP Server

Instructions

Implementation Reference

• src/index.ts:366-410 (handler)

  The handler function createLSI that executes the tool logic: creates a DynamoDB table with a local secondary index (LSI) using CreateTableCommand, since LSIs must be defined at table creation time.

  async function createLSI(params: any) {
    try {
      // Note: LSIs must be created during table creation, so we need the table's primary key info
      const command = new CreateTableCommand({
        TableName: params.tableName,
        AttributeDefinitions: [
          { AttributeName: params.partitionKey, AttributeType: params.partitionKeyType },
          { AttributeName: params.sortKey, AttributeType: params.sortKeyType },
        ],
        KeySchema: [
          { AttributeName: params.partitionKey, KeyType: "HASH" as const },
        ],
        LocalSecondaryIndexes: [
          {
            IndexName: params.indexName,
            KeySchema: [
              { AttributeName: params.partitionKey, KeyType: "HASH" as const },
              { AttributeName: params.sortKey, KeyType: "RANGE" as const },
            ],
            Projection: {
              ProjectionType: params.projectionType,
              ...(params.projectionType === "INCLUDE" ? { NonKeyAttributes: params.nonKeyAttributes } : {}),
            },
          },
        ],
        ProvisionedThroughput: {
          ReadCapacityUnits: params.readCapacity || 5,
          WriteCapacityUnits: params.writeCapacity || 5,
        },
      });
      
      const response = await dynamoClient.send(command);
      return {
        success: true,
        message: `LSI ${params.indexName} created on table ${params.tableName}`,
        details: response.TableDescription,
      };
    } catch (error) {
      console.error("Error creating LSI:", error);
      return {
        success: false,
        message: `Failed to create LSI: ${error}`,
      };
    }
  }

• src/index.ts:109-128 (schema)

  Tool definition including name, description, and input schema for validating parameters like tableName, indexName, keys, projection, etc.

  const CREATE_LSI_TOOL: Tool = {
    name: "create_lsi",
    description: "Creates a local secondary index on a table (must be done during table creation)",
    inputSchema: {
      type: "object",
      properties: {
        tableName: { type: "string", description: "Name of the table" },
        indexName: { type: "string", description: "Name of the new index" },
        partitionKey: { type: "string", description: "Partition key for the table" },
        partitionKeyType: { type: "string", enum: ["S", "N", "B"], description: "Type of partition key" },
        sortKey: { type: "string", description: "Sort key for the index" },
        sortKeyType: { type: "string", enum: ["S", "N", "B"], description: "Type of sort key" },
        projectionType: { type: "string", enum: ["ALL", "KEYS_ONLY", "INCLUDE"], description: "Type of projection" },
        nonKeyAttributes: { type: "array", items: { type: "string" }, description: "Non-key attributes to project (optional)" },
        readCapacity: { type: "number", description: "Provisioned read capacity units (optional, default: 5)" },
        writeCapacity: { type: "number", description: "Provisioned write capacity units (optional, default: 5)" },
      },
      required: ["tableName", "indexName", "partitionKey", "partitionKeyType", "sortKey", "sortKeyType", "projectionType"],
    },
  };

• src/index.ts:598-600 (registration)

  Registration of CREATE_LSI_TOOL in the list of available tools returned by ListToolsRequestSchema handler.

  server.setRequestHandler(ListToolsRequestSchema, async () => ({
    tools: [CREATE_TABLE_TOOL, UPDATE_CAPACITY_TOOL, PUT_ITEM_TOOL, GET_ITEM_TOOL, QUERY_TABLE_TOOL, SCAN_TABLE_TOOL, DESCRIBE_TABLE_TOOL, LIST_TABLES_TOOL, CREATE_GSI_TOOL, UPDATE_GSI_TOOL, CREATE_LSI_TOOL, UPDATE_ITEM_TOOL],
  }));

• src/index.ts:620-622 (registration)

  Dispatch registration in the CallToolRequestSchema switch statement that maps 'create_lsi' to the createLSI handler.

  case "create_lsi":
    result = await createLSI(args);
    break;